Adverse events: an expensive and avoidable hospital problem

Figures & data

Table 1. Prevalence of adverse events according to patient and hospital admission characteristics.

	Total	Prevalence of patients with AE
	n (%)	n	% (CI 95%)	p Value
Age*
Mean (SD)	66.5 (19.9)	71.9 (15.8)	68.3 to 75.4	0.021**
Median (IR)	70 (55 to 82)	75 (61 to 83)
Sex
Woman	305 (48.0)	33	10.8 (7.6 to 14.9)	0.240
Man	331 (52.0)	46	13.9 (10.3 to 18.1)
Type of admitting service
Medical specialities	295 (46.4)	34	11.5 (8.1 to 15.7)	<0.001***
Surgical specialities	268 (42.1)	31	11.6 (8.0 to 16.0)
Intensive medicine	36 (5.7)	13	36.1 (20.8 to 53.8)
Psychiatric	19 (3.0)	0	0.0 (0.0 to 17.6)
Paediatrics	18 (2.8)	1	5.6 (0.1 to 27.3)
Hospital stay before screening*
Mean (SD)	12.5 (22.7)	28.0 (43.0)	18.4 to 37.7	<0.001***
Median (IR)	5 (2 to 13)	13 (6 to 32)
Type of admission
Urgent	422 (66.3)	57	13.5 (10.4 to 17.1)	0.244
Scheduled	214 (33.7)	22	10.3 (6.6 to 15.2)
Surgical intervention
No intervention	395 (62.1)	40	10.1 (7.3 to 13.5)	0.025**
Intervention	241 (37.9)	39	16.2 (11.8 to 21.5)
Charlson index
≤ 1	201 (31.7)	16	8.0 (4.6 to 12.6)	0.065
2 to 3	226 (35.6)	32	14.2 (9.9 to 19.4)
≥ 4	208 (32.8)	31	14.9 (10.4 to 20.5)
Number of intrinsic risk factors
Absence	44 (6.9)	1	2.3 (0.0 to 12.0)	0.014**
1	98 (15.4)	10	10.2 (5.0 to 18.0)
2	123 (19.3)	10	8.1 (3.9 to 14.4)
≥ 3	371 (58.3)	58	15.6 (12.1 to 19.7)
Number of extrinsic risk factors
Absence	154 (24.2)	10	6.5 (3.2 to 11.6)	<0.001***
1	340 (53.5)	37	10.9 (7.8 to 14.7)
2	104 (16.3)	22	21.1 (13.8 to 30.3)
≥3	38 (6.0)	10	26.3 (13.4 to 43.1)
Intrinsic risk factors****
Cardiovascular disease	346 (54.4)	57	16.5 (12.7 to 20.8)	<0.001***
Impaired mobility	239 (37.6)	44	18.4 (13.7 to 23.9)	<0.001***
Hypoalbuminaemia	201 (31.6)	38	18.9 (13.7 to 25.0)	<0.001***
Pressure ulcers	33 (5.2)	13	39.4 (22.9 to 57.9)	<0.001***
Extrinsic risk factors****
Peripheral venous catheter	415 (65.3)	60	14.5 (11.2 to 18.2)	0.039**
Urinary catheter	134 (21.1)	28	20.9 (14.3 to 28.8)	<0.001***
Central venous catheter	109 (17.1)	22	20.2 (13.1 to 28.9)	0.008**
Death
No	596 (93.7)	67	11.2 (8.8 to 14.1)	<0.001***
Yes	40 (6.3)	12	30.0 (16.6 to 46.5)
Total	636 (100.0)	79	12.4 (10.0 to 15.2)

AE: healthcare-related adverse events; SD: standard deviation; IR: interquartile range; CI 95%: 95% confidence interval.

P for percentage difference: using chi-square tests (if parametric test conditions are met) and Fisher’s exact test (non-parametric).

P for quantitative variables: using Mann–Whitney U when normal criteria are not met.

*Age and hospital stay before screening are numerical variables. Mean and median are shown. CI 95% estimated is for the mean of patients with AE; **p < 0.05; ***p < 0.001; ****In intrinsic and extrinsic factors, only those that showed association are shown. The supplementary material includes the analysis of all factors.

Figure 1. Study diagram and results by phase. AE: health care-related adverse events; %: Prevalence data; MRF2: modular review Form 2.

Table 2. Association between death and detection of AEs.

	Total, n (%)	Deaths by group, n (%)	Odds ratio	CI 95%	p Value
Adverse event
No	557 (87.6)	28 (5.0)	1.00	NA	NA
Yes	79 (12.4)	12 (15.2)	2.15	1.07 to 4.52	0.032**
Age*
One-year increase, mean in sample years (sd)	66.5 (19.9)	77.7 (11.9)	1.04	1.01 to 1.07	0.009**
Sex
Women	305 (48.0)	13 (4.3)	1.00	NA	NA
Men	331 (52.0)	27 (8.2)	2.16	1.01 to 4.64	0.049**
Charlson index
≤ 1	201 (31.7)	7 (3.5)	1.00	NA	NA
2 to 3	226 (35.6)	13 (5.8)	0.79	0.23 to 2.81	0.722
≥ 4	208 (32.8)	20 (9.6)	1.34	0.36 to 5.03	0.664
Type of admission
Scheduled	214 (33.7)	1 (0.5)	1.00	NA	NA
Urgent	422 (66.3)	39 (9.2)	17.11	6.33 to 46.26	<0.001***
Type of service
Medical specialities	295 (46.4)	26 (8.8)	1.00
Surgical specialities	268 (42.1)	7 (2.6)	0.64	0.24 to 1.74	0.384
Intensive medicine	36 (5.7)	7 (19.5)	5.77	1.74 to 19.15	0.004**
Paediatrics	19 (3.0)	0 (0.0)	NA	NA	NA
Psychiatry	18 (2.8)	0 (0.0)	NA	NA	NA
Constant			0.00	0.00 to 0.01	<0.001***

CI 95%: 95% confidence interval; p: estimated p-value in logistic regression.

Multivariate analysis by logistic regression of the association between death and AE, adjusted by age, sex, Charlson index, type of income and type of service.

*Age is a numerical variable; **p < 0.05; ***p < 0.001.

Table 3. Types of AE and their impact by avoidability.

	Avoidability of AE
	Total	Not avoidable		Avoidable
	n (%)	n	% (CI95%)	n	% (CI95%)	p Value
Types of AE
Healthcare-related infections	53 (45.3)	18	52.9 (35.1 to 70.2)	35	42.2 (31.4 to 53.5)	<0.001**
Complications of a procedure	27 (23.1)	13	38.2 (22.2 to 56.4)	14	16.9 (9.5 to 26.7)
Complications in care	24 (20.5)	0	0.0 (0.0 to 10.3)	24	28.9 (19.5 to 39.9)
Adverse effects of medication	8 (6.8)	2	5.9 (0.7 to 19.7)	6	7.2 (2.7 to 15.1)
Other AE	5 (4.3)	1	2.9 (0.1 to 15.3)	4	4.8 (1.3 to 11.9)
The time of health care at which the AE occurred
Before admission	22 (18.8)	8	23.5 (10.7 to 41.2)	14	16.9 (9.5 to 26.7)	0.916
During admission	2 (1.7)	0	0.0 (0.0 to 10.3)	2	2.4 (0.3 to 8.4)
During a procedure	12 (10.3)	4	11.8 (3.3 to 27.5)	8	9.6 (4.3 to 18.1)
After the procedure	13 (11.1)	4	11.8 (3.3 to 27.5)	9	10.8 (5.1 to 19.6)
On the ward	66 (56.4)	18	52.9 (35.1 to 70.2)	48	57.8 (46.5 to 68.6)
At the end of admission	2 (1.7)	0	0.0 (0.0 to 10.3)	2	2.4 (0.3 to 8.4)
Severity
Mild	47 (40.2)	5	14.7 (4.9 to 31.1)	42	50.6 (39.4 to 61.8)	<0.001**
Moderate	36 (30.8)	18	52.9 (35.1 to 70.2)	18	21.7 (13.4 to 32.1)
Severe	34 (29.1)	11	32.4 (17.4 to 50.5)	23	27.7 (18.4 to 38.6)
Additional assistance as a result of the AE
Healthcare was not affected	1 (0.9)	0	0.0 (0.0 to 10.3)	1	1.2 (0.0 to 6.5)	0.793
It required only additional observation	4 (3.4)	2	5.9 (0.7 to 19.7)	2	2.4 (0.3 to 8.4)
Only required one additional test	2 (1.7)	1	2.9 (0.1 to 15.3)	1	1.2 (0.0 to 6.5)
Medical treatment or rehabilitation	75 (64.1)	20	58.8 (40.7 to 75.4)	55	66.3 (55.1 to 76.3)
Additional surgical intervention	22 (18.8)	7	20.6 (8.7 to 37.9)	15	18.1 (10.5 to 28.0)
Life support intervention or treatment	13 (11.1)	4	11.8 (3.3 to 27.5)	9	10.8 (5.1 to 19.6)
Affect of AE on stay
It did not lengthen the stay	48 (41.0)	5	14.7 (4.9 to 31.1)	43	51.8 (40.6 to 62.9)	<0.001**
Part of the stay	48 (41.0)	23	67.7 (49.5 to 82.6)	25	30.1 (20.5 to 41.8)
Cause of re-admission	20 (17.1)	6	17.7 (6.8 to 34.5)	14	16.9 (9.5 to 26.7)
Unknown	1 (0.9)	0	0.0 (0.0 to 10.3)	1	1.2 (0.0 to 6.5)
Additional days of hospitalization caused by Aes
Mean (SD)	17.3 (40.8)	24.1 (54.8)	4.92 to 43.2	14.5 (34.4)	6.9 to 22.0
Median (IR)	4 (0 to 19)	15 (2 to 20)		0 (0 to 12)		0.002*
Average daily economic cost per AE	€268.9 / day	€257.9 /day		€273.4 /day
Total (Days)	2,001	818		1,183
Total economic cost	€ 558,326.8	€ 227,103.8		€ 331,223.0
Additional days of ICU stay caused by AEs
Mean (SD)	1.7 (5.7)	1.6 (4.5)	0.1 to 3.2	1.8 (6.3)	0.5 to 3.2
Median (IR)	0 (0 to 0)	0 (0 to 0)		0 (0 to 0)		0.952
Average daily economic cost per AE	€1,712 /day	€1,841.6 /day		€1,658.5 /day
Total (Days)	206	55		151
Total economic cost	€ 351,390.0	€ 100,980.0		€ 250,410.0
Total	117 (100)***	34	29.1 (21.0 to 38.2)	83	70.9 (61.8 to 79.0)

AE: healthcare-related adverse events; SD: standard deviation; IR: interquartile range.

P for percentage difference: Chi2 (if parametric test conditions are met) and Fisher’s exact test (non-parametric).

P for quantitative variables: using Mann–Whitney U when normal criteria are not met.

*p < 0.05; **p < 0.001; ***4 AE of unknown avoidable nature are excluded.

Table 4. Risk factors associated with avoidable AE records.

	Total, n (%)	Avoidable AE, n (%)	Odds Ratio	CI 95%	p Value
Intrinsic risk factors (1)
Impaired mobility	260 (39.4)	51 (19.6)	2.24	1.35 to 3.71	0.002*
Cardiovascular disease	382 (57.9)	66 (17.3)	2.24	0.96 to 5.21	0.061
Pressure ulcers	41 (6.2)	16 (39.0)	2.77	1.39 to 5.51	0.004*
Extrinsic risk factors (1)
Central venous catheter	139 (21.2)	34 (24.5)	2.58	1.33 to 5.00	0.005*
Type of service
Medical specialities	310 (46.2)	33 (10.7)	1.00	NA	NA
Surgical specialities	272 (40.5)	31 (11.4)	1.41	0.73 to 2.72	0.220
Intensive care unit	52 (7.8)	18 (34.6)	2.75	1.07 to 7.06	0.036*
Psychiatric	19 (2.8)	0 (0.0)	1.00	NA	NA
Paediatrics	18 (2.7)	1 (5.6)	0.58	0.15 to 2.28	0.439
Constant			0.29	0.01 to 0.06	<0.001**

CI 95%: Confidence interval of 95%; p: estimated p-value in logistic regression; (1) Reference value: absence of factors.

Multivariate analysis by logistic regression adjusted by type of service, IRF and ERF.

*p < 0.05; **p < 0.001.

Data availability statement

The data that support the findings of this study are available from the corresponding author, JVG, upon reasonable request.