The relation between out-of-home care, early school failure, and premature mortality: a 30-year follow-up of people treated for substance misuse in Sweden

ABSTRACT

Evidence from Swedish and international studies show that a high proportion of children from out-of-home care (OHC) have poor school performance and that this is strongly associated with their substantial risk of adverse development in future life. However, risk factors for poor school performance and adverse development are difficult to disentangle since they are often interrelated and enforce each other over the life course. This study examines premature mortality in relation to early school failure (drop-out from compulsory school) and OHC experience in childhood (0–17 years of age) among clients who were in treatment for substance misuse in the early 1980s (N = 1,036). The analyses were based on record linkages between interview data collected during treatment and national register data covering approximately 30 years of follow-up, from exit from treatment until 2013. Our results showed that 54 per cent had been placed in OHC as children, half before their teens and half as teenagers. The OHC population had a higher prevalence of school failure compared with clients who had not been exposed to childhood OHC. OHC was associated with an excess mortality, although this was only significant for females who had entered OHC before their teens. Adjusting results for school failure reduced their excess mortality by half, and additional life course factors associated with mortality among people with substance misuse adjusted for most of the remaining excess mortality. School failure was strongly associated with the excess mortality of females, but not with the excess mortality of males.

KEYWORDS:

• Mortality
• out-of-home care
• foster care
• substance misuse
• school failure

Introduction

Out-of-home care (OHC) is a statutory intervention used by the social welfare services to protect children whose safety and welfare are at risk due to an adverse home environment or their own disruptive behaviour. Young people from OHC do often have a more disadvantaged social background than same-aged peers, especially those who enter OHC in young age where the reason for OHC relates to the parents’ social problems (Vinnerljung and Andreassen 2015). Evidence from Swedish and international studies show that a substantially proportion of children in OHC have poor school performance (e.g. Kääriälä and Hiilamo 2017; Gypen et al. 2017) and that this is strongly associated with their excess risk of adverse outcomes in future life e.g. substance misuse (Berlin, Vinnerljung, and Hjern 2011; Frønes 2016). Education is also a main factor for future opportunities in modern societies due to its importance for establishment in the labour market (Hout and DiPrete 2006). This is especially valid for young people from disadvantaged social background. In labour market segments where other qualifications than education are decisive, social networks and ascribed characteristics become more important (Breen and Jonsson 2007).

The risk of adverse development in childhood and adolescence is often an accumulative process where different risk factors are linked and enforce each other (Ferraro, Schafer, and Wilkinson 2016). This makes it hard to disentangle different risk factors over the life course. In studies concerning the OHC population it is also difficult to find an adequate comparison group and avoid that OHC merely mediates a marginalized social background. In this study, we have overcome some of these methodological problems by using a study population who were in residential treatment due to substance misuse and thus, more homogenous in regards to background factors associated with substance misuse, for example, psychosocial factors (Stone et al. 2012). The entire study population (N = 1,036) participated in the Swedish Drug Addict Treatment Evaluation (SWEDATE) research project. The data material were collected during their time in residential treatment for substance misuse in Sweden in 1982–1983 and provided self-reported information on background factors over the life course such as living conditions, education, employment, and substance misuse. Follow-up data (mortality and criminal convictions) were retrieved from high quality national registers covering approximately 30 years, from exit from treatment until 2013. The aim of this study was to investigate: (1) the prevalence of early school failure (not finished compulsory school) in relation to OHC experience, and (2) how that related to the risk of premature mortality when controlling for life course factors associated with mortality among people with substance misuse. Sex-specific models were used since previous studies suggest that the mortality pattern differ between men and women with substance misuse (e.g. Tuchman 2010; Von Greiff et al. 2018; Skogens et al. 2018).

Previous research on school failure in the OHC population

Evidence from a vast body of research, show that poor school performance is prevalent in the OHC population (e.g. O’Higgins, Sebba, and Gardner 2017) and that leaving care without an adequate education is strongly associated with the excess risk of adverse outcomes in future life, for example, substance misuse and mortality (Kääriälä and Hiilamo 2017; Gypen et al. 2017). Early OHC is usually caused by neglect or maltreatment, and it is well known that early family environments are major predictors of children’s cognitive and non-cognitive abilities (Heckman 2014). In comparison to the general population, there is a high prevalence of behavioural problems in the OHC population and evidence suggests that this is a risk factor for poor school performance in the OHC population (e.g. O’Higgins, Sebba, and Gardner 2017; Pears, Kim, and Brown 2018). Results from studies on the link between cognitive ability and poor school performance have been mixed (O’Higgins, Sebba, and Gardner 2017). In Swedish studies, the OHC population has been found to perform at a lower level than peers in the majority population regardless of cognitive ability (Vinnerljung, Berlin, and Hjern 2010) and accumulated knowledge gaps have been found to be the main factor behind children in OHC performing below their potential (Männistö and Pirttimaa 2018). In a recent review by O’Higgins and colleagues, the most consistent risk factors for poor school performance were male gender, ethnic minority status, behavioural problems and special education needs, while caregivers’ involvement in schooling and children’s aspirations and interest in school were the most consistent protective factors (O’Higgins, Sebba, and Gardner 2017).

Teen OHC experience is most often due to the child’s own disruptive behaviour, for example, substance misuse and delinquency (Vinnerljung and Andreassen 2015), which is interlinked with poor school performance and might be regarded as a two-way street, since poor school performance may also cause conduct problems (Gustafsson et al. 2010). High levels of psychiatric problems and the use of psychotropic drugs in the OHC population have been found in recent studies, both while in care (Socialstyrelsen 2014) and after care (Vinnerljung and Hjern 2014; Zlotnick, Tam, and Soman 2012). Studies on the effect of school support interventions aimed at the OHC population show that when school performance is boosted, behavioural problems decrease and interactions with friends and teachers improve as well as the children’s self-esteem (Männistö and Pirttimaa 2018).

Previous research on predictors of mortality in the OHC population

Research on mortality in the OHC population is scarce (Manninen et al. 2015; Vinnerljung and Ribe 2001), presumably due to the lack of data. In 2014, the crude mortality rate was approximately three times higher among Swedish adolescents (aged between 16 and 26) with OHC experience compared to the general population without OHC experience (Socialstyrelsen 2016a). The OHC population’s mortality rate has been fairly stable over the last few decades and in the cohorts born between 1960 and 1990 approximately 2 per cent were deceased by the age of 25 (Socialstyrelsen 2016b). Results from previous research suggest that the excess mortality compared to the general population occurs after the care has been terminated, with a later peak for females (after the age of 30) compared to males (23–28) (Manninen et al. 2015), and continues into midlife (Gao, Brännström, and Almquist 2017). In a Danish study, the mortality risk was approximately three times higher in the OHC population compared to peers in the majority population at the age of 27, with adjustment for parental background factors including psychiatric disorders, substance misuse, educational attainment, and unemployment (Nygaard Christoffersen 1999). Almquist et al. (2018) found that the OHC population lost almost a decade in life expectancy between the ages of 20 and 56 in comparison to peers in the majority population without OHC experience, and that school failure was strongly associated with the excess mortality. Evidence suggests that the risk factors for school failure and excess mortality are similar and intertwined with, for instance, behavioural disorders, substance misuse, and mental health problems including suicidal behaviour (Manninen et al. 2015; Nygaard Christoffersen 1999; Hjern, Vinnerljung, and Lindblad 2004; Kalland et al. 2001; Berlin, Vinnerljung, and Hjern 2011).

The excess mortality in the OHC population has been found to be primarily due to external causes such as substance misuse and injuries (intentional and unintentional). In a Swedish national cohort study, the risk of avoidable deaths (deaths from external causes and natural causes that could have been avoided with proper medical care) between the ages of 13 and 27 was three to four times higher in the OHC population compared to the majority population, which was partly due to the psychosocial characteristics of the original home environment (Hjern, Vinnerljung, and Lindblad 2004). When young people from a similar upbringing environment as the OHC population, but without OHC experience, were used as a comparison group in another Swedish study, the all-cause mortality risk between the ages of 19 and 26 for both groups was approximately twice as high compared with peers in the majority population (Vinnerljung and Ribe 2001). A Finnish study (Manninen et al. 2015) on mortality among teens who had been in residential care (on average, 15 years old at the baseline and 22 at the follow-up) found that all excess mortality in the residential care population was due to external causes, and that the single most common cause of death was substance-related. The risk of death from diseases and other medical conditions was not elevated in comparison with the majority population.

Material and methods

This study was based on record linkages between the SWEDATE data and two national registers: The National Cause of Death Register (CDR) held by the National Board of Health and Welfare, and the Register of Criminal Offences (RCO) held by The Swedish National Council for Crime Prevention. Data were linked by using the unique personal identity numbers given to all Swedish residents. The overall quality of the national registers is regarded as high. The SWEDATE data was originally collected through structured interviews by the Swedish Drug Addict Treatment Evaluation (SWEDATE) research project on people treated for substance misuse in 31 inpatient treatment units in Sweden in the period 1982–1983 (Olsson 1988; Bergmark et al. 1994). Clients with different types of substance misuse were mixed at the treatment units and 1,163 of 1,656 clients participated in the research project. The main reason for non-response was dropout from treatment before the interview was initiated. The quality of the SWEDATE data has been found to be high according to an overall evaluation (Olsson 1988).

Participants lacking complete information on OHC experience (50 individuals) and completion of compulsory school (1 individual) were excluded from the study. The study population was also restricted to participants who entered treatment before the age of 36 (8% entered treatment at an older age; 36–55). With those restrictions, the study population consisted of 1,036 participants who were followed in the registers from the year of exit from treatment until death or the end of the follow-up (December 2013). Exit from treatment occurred during a fairly narrow timespan (1982–1986). The outcome variable was death, retrieved from the CDR.

Study groups – out-of-home care experience during childhood

The study population was divided into three separate study groups according to OHC in childhood (0–17 years of age):

1) No OHC: No experience of OHC in childhood (N = 476).

2) Early OHC exposure: First placed in OHC before teens (at 0–12; N = 276).

3) Teen OHC exposure: First placed in OHC as a teenager (at 13–17; N = 284).

In total, 54 per cent (N = 560) had been placed in OHC as children, half before their teens and half as teenagers. Experience of OHC was defined according to self-reported experience of care except of 2 participants who were included in the teen OHC group since they entered the treatment for substance misuse that constituted our study population before they turned 18 years of age. The reason of early OHC is usually parents’ social problems while the reason of teen OHC is usually the adolescent’s own anti-social behaviour e.g. substance misuse (Vinnerljung and Andreassen 2015). Hence, in this study where the entire population was in residential care because of substance misuse, the distinction between the teen OHC group and the group without childhood OHC experience might only be the age of entry into care (or treatment).

Background variables

The choice of control variables was guided by prior research and the data available. All control variables apart from criminal convictions were retrieved from SWEDATE and refer to self-reported conditions collected using questions with fixed response options. School failure (dichotomous variable) refers to Not completed compulsory school education. No vocational training (dichotomous variable) and No regular employment > 1 year (dichotomous variable) covers the entire time period before treatment which varies in length depending on the age of the study subjects at their entry into treatment. Parental alcohol abuse (category variable) was created out of two separate questions concerning the respective alcohol consumption of the mother and father (birth, step, foster, or adoptive) during childhood (response options; absolutist; minor consumption; modest consumption; major consumption; and alcoholic). Parental alcohol abuse was defined as the respondent answering that the parents were alcoholics and measured in four mutually exclusive categories; both alcohol abuse; mother alcohol abuse; father alcohol abuse; and neither alcohol abuse. If there was only information on one of the parents, the category applies to that parent: ‘Neither’ if not alcoholic, or ‘Mother’ and ‘Father’ respectively if alcoholic. Psychiatric care and/or suicide attempts (dichotomous variable) were created out of two separate questions: one pertaining to having received psychiatric care (not including treatment for substance misuse) and one pertaining to suicide attempts. Daily contact with friends in the 12 months before intake (category variable) was created out of two separate questions on contacts with non-addict and addict friends respectively and measured in four mutually exclusive categories; no daily contact with friends; daily contact only with addicts; daily contact only with non-addicts; and daily contact with both addicts and non-addicts. The predominant drug in the 12 months before intake (category variable) was divided into five mutually exclusive categories: Alcohol, Cannabis, Stimulants, Opiates and Other, according to the respondents self-reported predominant drug for that period (for more details on the categories, see Von Greiff et al. 2018).

Crime active years and Years in prison (both time-dependent variables) were retrieved from the RCO which holds information on criminal offences that have been settled by a public prosecutor or a court. Crime active years refers to number of calendar years, from exit from treatment until censoring, with convictions (one or several) regardless of the type of crime and sanction. Years in prison (incarceration) refers to the penalty period according to the sentence even though the actual time in prison is usually 2/3 of the penalty period.¹

Statistical analysis

The analyses were made in the SAS software package. Survival analyses were performed with the use of Cox regression (PROC PHREG) to estimate the mortality risks (Table 3). The analyses followed an approach where models were fitted in three steps in order to examine the relation between the risk factors of interest. Model 1 only included OHC experience, school failure was added in Model 2, and all control variables were included in Model 3. In Model 3, 41 men and 21 women were excluded due to missing information on specific covariates (8 vs. 2 on parental alcohol abuse, 11 vs. 7 on psychiatric care and/or suicide attempts, 24 vs. 14 on daily contact with friends last 12 months). Left-truncated age (person days) was used as the timescale, starting at the age at exit from treatment (baseline age), and ending at the age at death or the end of the follow-up (December 2013). The reason behind the choice of age as the timescale was to avoid bias which might occur when age is associated with the covariates (Canchola et al. 2003). Participants who were older than 35 when they entered the treatment for substance misuse (8% were excluded) were excluded from the study since we were interested in premature mortality. Sensitivity analyses were carried out by using different age restrictions and with similar results as those presented in the article.

Table 1. OHC experience in the study population. Percent and means

	Men			Women			All
	No	Early	Teen	No	Early	Teen	No	Early	Teen
	OHC	OHC	OHC	OHC	OHC	OHC	OHC	OHC	OHC
Age at entry in OHC (mean)	.	7.4	15.0	.	6.0	15.0	.	7.0	15.0
Type of OHC (%)
Foster care, family care	10	78	63	11	78	62	10	78	62
Children’s home	1	66	32	.	68	39	1	67	34
Residential school	4	45	40	2	44	25	3	45	34
All three types of OHC	1	44	17	0	44	18	1	44	17
Number of OHC periods (mean)
Foster care, family care	1.5	2.7	2.0	1.3	3.4	1.7	1.5	2.9	1.9
Children’s home	1.0	2.0	1.6	.	2.2	1.4	1.0	2.1	1.5
Residential school	2.7	2.9	1.7	1.0	1.8	1.5	2.5	2.6	1.6
All three sorts	2.0	5.1	2.9	1.2	5.2	2.3	1.8	5.1	2.7
Number (N)	341	192	181	135	84	103	476	276	284
Percent in study groups	48	27	25	42	26	32	46	27	27

Table 2. Distribution of background factors. Per cent (%)

	Men			Women			All
	No	Early	Teen	No	Early	Teen	No	Early	Teen
	OHC	OHC	OHC	OHC	OHC	OHC	OHC	OHC	OHC
Age at intake (mean years)	26.0	26.2	24.7	24.6	23.7	22.3	25.6	25.4	23.8
Parental alcohol abuse
Missing information	1	2	1	1	.	.	1	1	1
Both	0	4	.	1	7	4	1	5	1
Mother	1	3	2	2	8	5	1	5	3
Father	17	21	10	18	17	14	17	20	11
Neither	81	70	87	77	68	78	80	70	83
Not finished compulsory school*	13	28	27	15	43	32	14	33	29
No vocational training*	58	67	72	68	73	80	61	69	75
No regular employment > 1 year*	22	42	48	37	62	67	26	48	55
Psychiatric care or suicide attempts*	34	51	39	39	68	54	36	56	44
Predominant drug last 12 months
Alcohol	23	22	24	16	19	17	21	21	21
Cannabis	27	25	22	13	19	16	23	23	19
Stimulants	30	38	37	38	45	37	32	40	37
Opiates	17	9	13	27	13	24	20	10	17
Other	4	6	4	7	4	6	5	5	5
Daily contact last 12 months
Missing information	5	2	2	4	4	5	5	3	3
Neither addicts nor non-addicts	17	14	14	26	17	12	20	15	13
Only with non-addicts	10	6	10	7	6	5	9	6	8
Only with addicts	57	66	58	54	68	67	56	66	61
Both with addicts & non-addicts	11	12	15	9	6	12	11	10	14
Criminal convictions after exit from treatment
Years in prison (mean)	2.1	3.1	3.1	0.4	0.8	0.6	1.6	2.4	2.2
Crime active years (mean)	5.9	8.7	8.6	4.5	5.0	4.0	5.5	7.6	6.9
No criminal offences (not in RCO)	6	2	2	19	8	15	10	4	6
Combination of psychiatric care & school failure
None	55	35	44	52	17	30	54	29	39
Only school failure	9	14	14	8	12	13	9	13	14
Only psychiatric care	30	36	27	33	39	36	31	37	30
Both	4	14	12	7	29	18	5	18	14
Deceased at end of 2013	41	47	45	20	35	23	35	43	37
Among:
No school failure	40	47	46	17	29	16	33	42	35
School failure	50	46	44	35	42	39	45	44	42
Total number (N)	341	192	181	135	84	103	476	276	284

* Dichotomous variable.

Table 3. Mortality risks (HR). Cox regression with age-scale

	Men						Women
	Model 1		Model 2		Model 3		Model 1		Model 2		Model 3
	HR	P	HR	P	HR	P	HR	P	HR	P	HR	P
Childhood OHC
No	1 (ref.)		1 (ref.)		1 (ref.)		1 (ref.)		1 (ref.)		1 (ref.)
Early	1.13	0.38	1.12	0.42	0.85	0.29	1.84	<.05	1.40	0.24	1.06	0.87
Teen	1.24	0.13	1.23	0.15	1.01	0.94	1.38	0.26	1.23	0.47	1.04	0.91
School failure*			1.07	0.62	0.95	0.73			2.14	<.01	1.98	<.05
Parental alcohol abuse
Both					2.12	0.11					3.08	<.05
Mother					0.86	0.72					1.26	0.71
Father					0.95	0.73					0.94	0.86
Neither					1 (ref.)						1 (ref.)
No vocational training*					0.92	0.50					0.98	0.95
No regular employment > 1 year*					1.32	<.05					1.49	0.17
Psychiatric care and/or suicide attempts*					1.28	<.05					1.55	0.10
Predominant drug last 12 months
Alcohol					1.50	<.05					2.22	<.05
Cannabis					1.19	0.33					0.43	0.18
Stimulants					1 (ref.)						1 (ref.)
Opiates					2.46	<.01					2.55	<.01
Other					1.44	0.26					2.37	0.15
Daily contact last 12 months
Neither addicts nor non-addicts					1.19	0.49					1.17	0.78
Only with non-addicts					0.90	0.73					1.43	0.62
Only with addicts					1.37	0.15					1.48	0.43
Both with addicts & non-addicts					1 (ref.)						1 (ref.)
Criminal convictions after exit from treatment
Years in prison (time-dependent)					0.93	<.01					0.93	0.39
Crime active years (time-dependent)					1.12	<.01					1.15	<.01
Total number (N)	714		714		673		322		322		301

* Dichotomous variable.

The time-dependent variables (Crime active years and Years in prison) were handled with the counting process method (Allison 2010) where the study subjects were represented with multiple records where each record corresponded to a time interval during which the covariates remained constant. Crime active years was measured as the cumulative number of years with criminal offences, and Years in prison as the cumulative penalty period (continuous).

Ethics

This research was scrutinized and approved by the Ethical Review Board in Stockholm, Sweden (2015/329-31/5, 2015/1205-32, 2016/542-32/5).

Results

Table 1 presents OHC experience in the study population, where 27 per cent had been placed in early OHC and 27 per cent in teen OHC, adding to a total of 54 per cent in childhood OHC. Teen OHC was more prevalent among female participants compared to male participants. The OHC experience differ between individuals and within the study groups, some stayed in OHC for a short period of time, while others stayed in OHC for most of their childhood, some stayed in one type of OHC while others stayed in various types of OHC (i.e. foster care, children’s home, or residential school). The participants in the early OHC group might also have been in OHC as teenagers, since the definitions of the study groups refer to the age at first entry into OHC.

In the early OHC group, the average age at first entry into OHC was 7.0 years of age and they had on average been in OHC 5.1 times during their childhood (78% had been in foster care, 67% in children’s home (response options also included homes for boys or girls and school homes), 45% in residential school (cf. approved school), and 44% in all three types of OHC). The proportions of various types of OHC do not add up to 100 per cent since many have been in different types of OHC during childhood. In the teen OHC group, the average age at first entry into OHC was 15.0 years of age and they had on average been in OHC 2.7 times during their childhood (62% had been in foster care, 34% in children’s home, 34% in residential school, and 17% in all three types of OHC). Some of those who had not been placed in OHC during their childhood i.e. the No OHC group in Table 1, had been placed in OHC as young adults (18–19 years of age) as a correcting or supportive measure due to e.g. substance misuse or criminality.

Table 2 presents the variables used in the analysis. Participants who experienced OHC in childhood had a higher prevalence of school failure (i.e. had not completed their compulsory school education) than peers with no childhood OHC exposure. Differences between study groups were greater among females than males. The high proportion of school failure in the OHC groups was not compensated by vocational training outside school, which was also less common in the OHC groups compared to peers. The proportion who had never had a regular job for a year (or more) was almost twice as high in the OHC groups compared to peers without childhood OHC experience. Parental alcohol abuse was most common in the early OHC group.

The teen OHC group was on average younger than the two other study groups at intake to treatment, and females were younger than males. Stimulants were more common as the predominant drug (12 months before intake) among males with childhood OHC experience (both early OHC and teen OHC), and females with experience of early OHC, compared to peers with no experience of OHC in childhood. Opiates were less common among females with early OHC experience as compared to peers. Psychiatric care (including suicide attempts) was more common in the OHC groups compared to peers without OHC exposure. The vast majority (more than 90%) had a criminal record (criminal offences according to the RCO) and the OHC groups at a slightly higher rate than those without OHC experience.

The percentage of deceased in the study population is presented both by study group and by school failure. Males with early OHC exposure had the highest proportion of deceased (47%) and females without OHC exposure the lowest proportion (20%). Among females, the proportion of deceased was higher among those with school failure compared to those who had completed their compulsory school education in all three study groups. That was not the case among males where the proportion of deceased among those who had failed at school was only higher in the non-OHC exposure group.

Table 3 presents the mortality risks (HR) in three different models, the first model without adjustment for control variables, model 2 with adjustment for school failure, and model 3 with adjustment for all control variables included in this study. The unadjusted mortality risk (measured as hazard ratios, HR) was higher among males in the OHC groups compared to males without childhood OHC experience (Model 1), albeit not to a significant extent. The OHC group’s excess mortality was higher among females, albeit only to a significant extent for the early OHC group (Model 1: HR = 1.84).

There was a significant association between school failure and the mortality risk of females (Model 2: HR = 2.14) and adjusted for nearly half of the excess mortality risk associated with early OHC exposure (Model 1 vs. Model 2: HR = 1.84 vs. HR = 1.40). For males, school failure was not a prominent risk factor for the mortality risk and accordingly had a minor influence on the excess mortality risk among males with OHC experience. For females, the excess mortality risk associated with school failure remained significant when additional factors (parental alcohol abuse, vocational training, work experience, psychiatric care, predominant drug, social networks, criminal convictions and prison time) were included in the analysis (Model 3: HR = 1.98), while the excess mortality associated with OHC experience almost disappeared. For both females and males, alcohol abuse and opiate abuse 12 months before intake to treatment were associated with an excess mortality as compared to stimulants. No regular employment (for at least a year) and previous psychiatric care was associated with an excess mortality, although this was only significant for males. Furthermore, there was a strong link between involvement with the criminal justice system after exit from treatment and the mortality risk, both for males and females. There was a positive association between the number of crime active years (time-dependent) and the mortality risk, while there was a negative association between time in prison (time-dependent) and the mortality risk, although it was only significant for males.

We combined school failure and previous psychiatric care in a separate analysis (Table 4). These results were in line with the analysis using independent variables, and previous psychiatric care was a more prominent risk factor for the excess mortality of males than school failure, although the combined categories were not significant. For females, school failure was still strongly associated with mortality regardless of whether it was combined with previous psychiatric care or not (HR = 2.76 vs. HR = 2.64).

Table 4. Mortality risks (HR). Cox regression with age-scale

	Men		Women
	Model 3		Model 3
	HR	P	HR	P
Combination of psychiatric care & school failure*
None	1 (ref.)		1 (ref.)
Only school failure	0.79	0.24	2.64	<.05
Only psychiatric care	1.18	0.23	1.80	0.08
Both	1.41	0.08	2.76	<.01

* Adjusted for the same variables as in Table 3, Model 3, but with psychiatric care and school failure as a combined variable instead of two independent variables.

Discussion

The present study investigated the relationship between childhood OHC, school failure and mortality among participants who were in treatment for substance misuse in Sweden in the early 1980s. First, our results showed that 54 per cent of the participants had experienced OHC during childhood. The corresponding proportion in the general population was approximately 4 per cent (Vinnerljung and Andreassen 2015). Second, school failure was more prevalent among those who had been in OHC compared with peers without OHC exposure. Third, without adjustment for control variables, childhood OHC was associated with an excess risk of mortality, albeit a modest link in males and only statistically significant in females in the early OHC group. Fourth, school failure was associated with an excess mortality among females, but not among males, and the inclusion of school failure in the analysis adjusted for half of the excess mortality associated with early OHC among females. Fifth, the strong association between school failure and mortality among females remained after adjusting for additional background factors known to be associated with mortality among people with substance misuse, while almost none of the excess mortality risk associated with early OHC remained.

In summary, the relation between childhood OHC, school failure, and premature mortality differed between the female and male participants. For female participants, there was an excess mortality associated with early OHC which seemed to be mediated through school failure, parental alcohol abuse, own alcohol or opiate misuse, and criminality. For male participants, childhood OHC and school failure were not significantly associated with an excess mortality, instead the significant risk factors were no regular employment, psychiatric care and/or suicide attempts, own alcohol or opiate misuse, and criminality. A similar gender difference in the linkage between childhood disadvantage and social exclusion in the general population has been reported in a previous Swedish study i.e. no direct link between social problems in the family of origin and educational achievements for men but for women. Overall, the results showed no direct links between childhood disadvantage and social exclusion, instead the effects were mediated by other risk factors over the life course (Bäckman and Nilsson 2011).

The high prevalence of childhood OHC experience in the study population, including early OHC exposure, confirms previous research that identifies OHC as a risk factor for substance misuse in adolescence and adulthood (e.g. Kääriälä and Hiilamo 2017; Gypen et al. 2017) and that this in turn is one reason for their excess mortality compared to the general population (Hjern, Vinnerljung, and Lindblad 2004; Manninen et al. 2015). However, it has been argued that general population studies that compare individuals with and without OHC experience merely mediate a marginalized social upbringing rather than a negative influence caused by OHC (cf. Vinnerljung and Ribe 2001). This study manages to deal with this criticism to a certain extent since one adverse outcome – substance misuse – applies to the entire study population rendering the study population more homogenous with regard to background factors associated with substance misuse, for example, psychosocial factors (Stone et al. 2012). Hence, the present study adds to previous research by showing that early childhood OHC was significantly associated with an excess mortality for females – also among individuals with documented substance misuse – and that school failure adjusted for half of their excess mortality.

Our results also support the large body of research that shows a high prevalence of poor school performance in the OHC population as compared with peers (e.g. O’Higgins, Sebba, and Gardner 2017) and adds to these findings by concluding that this was also valid among participants in treatment for substance misuse. Among females with early OHC experience, the proportion failing at school was almost three times higher than for females without OHC experience. Evidence from previous research suggests that children whose birth parents have substance misuse enter care at a younger age and stay in OHC for longer periods of time (Von Borczyskowski, Vinnerljung, and Hjern 2013). Our results showed that parental alcohol abuse was more common in the early OHC group than in the other study groups and that there was a link to excess mortality in the study subjects when both parents had abused alcohol during their childhood, albeit only statistically significant in females.

Even though the high proportion of school failure in the OHC groups is consistent with previous research, the differences between females and males were reversed. Generally, males have higher rates of school failure than females, both in the OHC population (O’Higgins, Sebba, and Gardner 2017) and in the general population (OECD 2018). In our study population, school failure was more common among females than among males in the OHC groups, and equally common among females and males without OHC experience. This implies that school failure was a more prominent risk factor for substance misuse among females (if we assume no gender bias in self-reported information on school failure) which resulted in a higher prevalence of school failure among female participants. This is also consistent with the strong association between school failure and mortality among female participants, indicating that the females in our study population were more marginalized than the males.

The excess mortality risk among female participants with early OHC experience, as compared with peers without OHC experience, was halved when results were adjusted for school failure. Even though school failure might be a mediator for all sorts of problems during compulsory school years, it is also likely to be a confounder for a less successful transition into adulthood and, thus, for greater difficulties in recovering from substance misuse. Vocational training did not compensate for the high prevalence of school failure in the OHC population and was less common in the OHC population, as was previous regular employment where there was a significant link (no regular employment) with the mortality of males as found in previous research (Evans et al. 2015).

The strong association between school failure and mortality among females remained when additional risk factors where included in the analysis. However, the remaining excess mortality associated with OHC disappeared. Previous research has shown that the excess mortality in the OHC population occurs after OHC has been terminated and is primarily due to external causes related to drug abuse, delinquency, and psychiatric problems (Manninen et al. 2015; Nygaard Christoffersen 1999; Hjern, Vinnerljung, and Lindblad 2004). Psychiatric problems and use of psychotropic drugs are highly prevalent in the OHC population (Socialstyrelsen 2014) and a risk factor for school failure (O’Higgins, Sebba, and Gardner 2017; Pears, Kim, and Brown 2018). Our results confirmed previous research that suggests that psychiatric problems are also a risk factor for premature mortality (e.g. Ravndal, Lauritzen, and Gossop 2015) and that females tend to have a higher prevalence of psychosocial problems than males when entering treatment (e.g. Tuchman 2010). When school failure and psychiatric care were treated as independent variables, there was only a significant link between psychiatric care and an excess mortality in males. We performed an interaction between previous psychiatric care and school failure in the last step of our analysis, which showed that these factors enhanced each other although the association was modest among males, and school failure alone remained a prominent risk factor in females. The vast majority in the study population also had a criminal record and as shown in previous studies, criminal activity was strongly associated with excess mortality (cf. Elonheimo, Sillanmäki, and Sourander 2017), while time in prison was associated with a decreased mortality risk (cf. Bacak and Wildeman 2015). Unlike a previous mortality study using the same data (Skogens et al. 2018), there was no significant link between the social network variable (daily contact with addicts and non-addicts) and the mortality risk in males, which is in all likelihood a consequence of the criminal activity variable in the analysis.

Adverse development is often an accumulative process where different risk factors are linked and enforce each other over the life course (e.g. Ferraro, Schafer, and Wilkinson 2016; Bäckman and Nilsson 2011). Our results showed that the OHC population did not only constitute a large proportion of the participants in treatment for substance misuse, they also had a higher prevalence of school failure as well as other adverse outcomes over the life course (e.g. psychiatric care, no regular employment, and criminal activity) compared with participants without OHC experience. This highlights the importance of early measures to identify and prevent an adverse development while children are in OHC. Preventing school failure is vitally important for improving children’s future opportunities as well as their wellbeing and self-esteem at present. There are promising results from support programmes which aim at improving school performance among children in care. Tutoring programs have so far had the best empirical support but several other interventions have also shown good results. Furthermore, results indicate that when school performance is boosted, behavioural problems decrease and relations with friends and teachers improve (Forsman and Vinnerljung 2012; Männistö and Pirttimaa 2018). Even though education is not the only yardstick for a successful transition into adulthood, there is reason to believe that this is especially important for young people from OHC since many will have weak support as they enter adulthood. Evidence shows that there is a gap between the needs of young people ageing out from care and the support they receive from the society, and that these patterns cut across countries and time (Cameron et al. 2012; Höjer and Sjöblom 2010). Yet, intervention studies are scarce and far more research is needed on how to improve future opportunities for children and youth from OHC.

Strengths and limitations

The strengths of this study were that we had a long follow-up period, approximately 30 years, and rich data material covering life course factors combined with national register data of high quality on mortality and criminal convictions. It also included the majority of clients that were treated for problems with drug abuse in Sweden in the early 1980s. An unavoidable limitation is that the long follow-up implicates that the OHC took place more than three decades ago (before 1982). However, evidence from Swedish data suggests that the prevalence of school failure and early death have remained stable throughout this period (Socialstyrelsen 2016a, 2016b). A more prevailing limitation is that we underestimated the mortality among the participants since we did not follow them from the substance use debut, and since the main reason for not being interviewed was dropout from treatment before the interview, which might indicate a more progressed abuse and a higher prevalence of adverse outcomes in this group. We may also have underestimated the excess mortality in the OHC groups compared to the group without OHC experience since previous research shows that the OHC groups have an excess mortality immediately after leaving OHC (Manninen et al. 2015). Another limitation is that the background information is self-reported, but that is also what makes the data material rich on information. The results in the tables are presented as descriptive statistics, rather than inferential statistics, since our study population is neither a random sample nor a total population, and thus the results should be interpreted with caution.

Acknowledgments

We are grateful to Professor Anders Bergmark, Department of Social Work, Stockholm University, who was a member of the research team leading the SWEDATE-project and who have supported the present follow-up project.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was funded by Forskningsrådet om Hälsa, Arbetsliv och Välfärd (Grant # 2015-00980).

Notes

¹Based on the penalty Act (SFS 1974:202).