Characteristics of the first 1000 clients attending an anxiety clinic in South West Sydney

Abstract

This paper reports on the clinical and demographic characteristics of the first 1000 consecutive patients attending an anxiety disorders clinic at a district hospital in Sydney, Australia. Data from a large epidemiological study of the Australian population were used as a yardstick for broad comparison. Contrary to past research, a lower prevalence of comorbid anxiety and depression was found in the clinic, possibly because a portion of those patients were filtered out and referred elsewhere for treatment for depression. More female patients attended the clinic than the epidemiological study would predict. Greater numbers of patients with panic disorder, and fewer with posttraumatic stress disorder and social phobia were seen in the clinic than would be predicted by the epidemiological data. Although inferences are tentative because of the differing methods of diagnosis used, the findings indicate the value of comparing epidemiological and clinic profiles to identify those categories of anxiety patients that underutilise services.

Epidemiological studies suggest that the majority of persons with psychological disorders do not obtain appropriate treatment (e.g., Henderson, Andrews, & Hall, 2000; Kessler et al., 1994). A recent Australian epidemiological study reported a 12-month prevalence of anxiety disorders of 9.7% (Australian Bureau of Statistics [ABS], 1997); but only 28% of this group sought help from a health professional, and most of these were treated by a general practitioner rather than at a specialist mental health service (Henderson et al., 2000). Low levels of service utilisation occurred despite sufferers reporting substantial impairment in their daily lives, consistent with findings from other countries (e.g., Kessler et al., 1994). Research suggests that the social costs of under-treating anxiety disorders may be high (Greenberg et al., 1999). In contrast, epidemiological studies such as those cited here have been criticised for potentially overestimating the true number of people with anxiety in need of specialist clinical interventions (Horwath, Lish, Johnson, Hornig, & Weissman, 1993). If so, it may be that clinic populations differ systematically from general population samples identified with anxiety. Further understanding of such putative differences is important in bridging the gap between epidemiological data and estimates of specialist service need.

Several characteristics may determine why some anxiety sufferers are more likely to be referred to a specialist anxiety clinic. The acuity of symptoms associated with panic disorder may increase referral of that disorder (Regier, Burke, & Burke, 1990), as compared to chronic disorders such as social phobia (Weiller, Bisserbe, Boyer, Lepine, & Lecrubier, 1996). Additionally, comorbidity may increase attendance at specialist clinics (Andrews, Slade, & Issakidis, 2002; Kessler et al., 1996; Roy-Byrne et al., 2000), especially where anxiety is comorbid with depression, the presence of which is associated with greater tendency to seek professional help (Hunt, 2000; Wittchen et al., 2002).

At the same time, several filters to care may determine whether certain demographic or diagnostic groups are referred to specialist clinics. General practitioners may be competent in recognising some disorders but not others, the high cost of treatment may deter some sufferers, as may geographical inaccessibility of clinics, and the application of exclusion criteria by some specialist treatment units may bias referral patterns.

Case identification procedures may also be responsible for real or spurious differences between clinic and population-wide samples. Most large-scale epidemiological surveys are undertaken by lay interviewers using forced-choice structured interviews, most commonly the Composite International Diagnostic Interview (CIDI) (World Health Organization, 1997). Diagnoses are not based on clinical experience or on discretion in reconciling overlapping criteria. Hence, procedural factors may increase the likelihood of comorbidity. Several studies have suggested that this approach may be less discriminatory in classifying patients when compared to diagnostic procedures applied by experienced clinicians (Horwath et al., 1993; Peters & Andrews, 1995). There is also a possibility that epidemiological surveys may be overly inclusive, detecting forms of anxiety that cause limited disability (Regier et al., 1998; Wittchen, 1998). For example, the enumeration of persons with nondisabling simple phobias may lead to inflated prevalence estimates (Regier et al., 1990).

We assumed that the clinical sample described herein was less likely to be affected by systemic filters than previously studied clinic populations because it was drawn from an anxiety clinic offering a free service. The service is well-known to most referral sources within the area (as described in Wagner, Manicavasagar, & Silove, 2002) and there are no other specialist options for treating anxiety for people residing in this locality.

The geographical area serviced by the clinic has a population of more than 700,000 persons, and is characterised by cultural diversity (34% of the population were born overseas) (Mohsin, Bauman, & Noble, 1997), higher-than-Australia-wide rates of unemployment (11%) (Epidemiology Unit, 2000), relatively low socioeconomic status and a larger number of older persons. A reciprocal arrangement is in place with other treatment units in the area whereby the clinic accepts anxiety referrals whereas those with other disorders such as depression are diverted outwards.

The aims of the present study were to examine whether demographic and/or diagnostic factors were associated with preferential attendance at the clinic. We also aimed to assess whether comorbidity was more prominent in the clinic population, as predicted by previous research. We realised at the outset that comparison of the clinic and epidemiological data could be only indicative given differences in the diagnostic procedures used.

Methods

Approval for the study was obtained from the Ethics Committee of the South Western Sydney Area Health Service (SWSAHS). Participation was entirely voluntary and subjects were informed of the confidential nature of any information gathered.

The demographic and clinical characteristics of the first 1000 consecutive patients attending the clinic after its inception were documented using structured reporting forms completed by experienced clinical psychologists. Although structured diagnostic instruments were not used in earlier cases, all treating psychologists underwent rigorous training in applying DSM-IV criteria for assigning anxiety diagnoses and their subcategories, with ongoing supervision and case discussions with the first author aiming to refine and standardise diagnostic approaches by all clinicians. All newly employed clinicians were required to audiotape clinical interviews during training, and the process continued until they reached 100% diagnostic agreement with the first author, who reviewed the tapes.

One change instigated at the clinic during the course of this study was the introduction of the anxiety and depression modules (excluding bipolar disorder) of the Structured Clinical Interview for the DSM-IV (SCID). Studies on the reliability of the SCID have obtained kappa values between .70 and 1.00 (First, Spitzer, Gibbon, & Williams, 1997). Of the 1000 cases reviewed here, 787 clients had clinical diagnoses supplemented by SCID diagnoses, which were undertaken by the same clinical psychologist on separate occasions. There was a 91% concordance between first diagnoses assigned by clinical and SCID diagnoses.

Data from the anxiety clinic were compared with an ABS study (ABS, 1997), a survey based on a representative sample of 10,600 persons drawn from across Australia (response rate, 78%). The ABS study utilised the CIDI to make diagnoses, while the anxiety clinic diagnoses were based upon DSM-IV criteria, which was implemented in both clinical and SCID diagnoses.

Results

Two thirds (68%, n = 685) of anxiety clinic patients were assigned a primary anxiety diagnosis, the remainder being referred to other agencies after assessment. The latter group was heterogeneous and included 8% with mood disorders and 10% with adjustment disorders. Nine per cent did not meet criteria for any diagnosis, and for 4% the diagnosis was unclear.

Of the 685 persons treated at the clinic, 49 were excluded from the present analysis because they suffered from an anxiety disorder not included in the ABS study (e.g., a specific phobia or an anxiety disorder due to substance abuse). This reduced the total number of clinic participants to 635, compared to 603 anxiety cases in the ABS study.

Referral source

Nearly half (49.6%) of clinic patients were referred by a general practitioner, 14% by public community mental health services, 12% by a private psychiatrist and 5% by a private psychologist. Twelve per cent were self-referred.

Demographic comparisons

Table I compares the demographic characteristics of the clinic and ABS samples.

Table I. Demographic data and drug and alcohol use: Clinic vs. epidemiological data

Variable	Anxiety clinic n (%)	ABS study n (%)
Total no. participants	635	603
Female	441 (69)**	365 (60)
Age 25 – 54	483 (76)	440 (73)
Age 65 +	50 (8)*	28 (5)
Married or live-in relationship	326 (51)	326 (54)
Australian-born	426 (67)***	467 (77)
Employed (FT or PT)	291 (46)**	320 (53)
Drug and alcohol use	137 (20)	137 (23)

Notes. ABS = Australian Bureau of Statistics; FT = full time; PT = part time. *p < .05; **p < .01; ***p < .001.

Gender

Proportionately more clinic patients with anxiety disorders were female (69%) compared to the ABS study (60%; p < .001, χ² = 10.8).

Age

The mean age for clinic patients was 43.5 years (SD = 13.5). Approximately three quarters (76%) were in the 25 – 54 age band, with 55% falling in the age range 25 – 44 years. Eight per cent were over 65 years. The age distribution for all but the over-65 group was similar to that reported in the ABS study (ABS, 1997). The larger proportion of participants in the older age group in Bankstown (p < .05, χ² = 5.5) may reflect the population demographics of the area (more older persons).

Marital status

No differences were found across the two samples in marital status, with 51% of clinic patients being married or in cohabiting relationships, compared to 54% in the ABS study.

Country of origin

Thirty-three per cent of clinic patients were born overseas, compared to 23% of anxiety patients in the ABS study (p < .001, χ² = 16.5). This difference appeared to be explained by 1996 census data, which reported a similar percentage (34.4%) of immigrants in the geographical area of the clinic. Likewise, the representation of immigrants in the Australia-wide population as a whole was almost identical (23.3%) to anxiety patients (23%) identified in the ABS study (Australian Department of Immigration and Multicultural Affairs, 2000).

Employment status

Forty-six per cent of clinic patients and 53% of participants in the ABS study were employed (p < .05, χ² = 6.5; Table I). Within the anxiety clinic sample, 11% were unemployed, 5% were retired or on an age pension, 4% received a disability pension and 7% were students. Twenty-two per cent were involved in home duties. The ABS study found that 8% of those with an anxiety disorder were unemployed and 35% not in the labour force for other reasons. The difference in unemployment across the two samples appeared to be attributable to the local characteristics of Bankstown, where the unemployment rate was 10.8% (ABS, 1996), with the national figure being 8%.

The unemployment rate of clinic patients by diagnosis was: social phobia, 17%, posttraumatic stress disorder (PTSD), 16%, panic disorder (with or without agoraphobia), 11%, generalised anxiety disorder (GAD), 9%, and obsessive – compulsive disorder (OCD), 8%.

Use of drugs and alcohol

Table I indicates that 20% of clinic patients consumed alcohol at a moderate or higher level (male patients consuming more than 5 – 6 and female patients more than 3 – 4 standard drinks per day, where 1 standard drink = 8 – 10 g of absolute alcohol). Only 5% admitted to present illicit drug use, with cannabis being the most frequently used drug.

The ABS study found that 23% of those with an anxiety disorder had a substance-use disorder (drug or alcohol) (ABS, 1997), a prevalence that did not differ from the clinic.

Clinical diagnosis

Table II compares anxiety clinic diagnoses to those yielded by the ABS survey (ABS, 1997).

Table II. Clinic and community diagnoses

Variable	Anxiety clinic n (%)	ABS study n (%)
PD and PD-Ag	315 (39)**	166 (21)
GAD	261 (33)	274 (34)
Social phobia	105 (13)*	147 (18)
PTSD	61 (8)**	147 (18)
Obsessive – compulsive disorder	58 (7)	77 (9)

Notes. ABS = Australian Bureau of Statistics; GAD = generalised anxiety disorder; PD = panic disorder; PD-Ag = PD with agoraphobia; PTSD = posttraumatic stress disorder. *p < .01; **p < .001.

The ABS study did not distinguish between primary and secondary diagnoses, instead listing multiple diagnoses where relevant. Thus the total number of diagnoses was larger than the total number of participants and the same method of enumeration was applied to the anxiety clinic data.

In the ABS study, GAD was the most common diagnosis (34%). Although GAD was equally common in the clinic (33%), panic disorder with or without agoraphobia was the most common presenting diagnosis (39%). This contrasted with the ABS study, in which panic/agoraphobia constituted the second most common anxiety category (21%).

PTSD and social phobia accounted for 8% and 13%, respectively, of clinic diagnoses. In contrast, the ABS study reported a higher prevalence for each of these disorders, ranking both equal third (18% for each diagnosis).

Seven per cent of clinic referrals were diagnosed with OCD, a similar prevalence to the ABS study (9%).

Comorbidity

Twenty three per cent (n = 144) of clinic attenders had more than one anxiety disorder (Table III), a percentage that was similar to the ABS study (26%). The clinic sample included 118 (19%) with both an anxiety disorder and a mood disorder, a markedly lower prevalence than in the ABS study (46%, p < .001, χ² = 106).

Table III. Comorbid diagnoses in clinic and community samples

Variable	Anxiety clinic n (%)	ABS study n (%)
Total no. participants	635	603
Total no. diagnoses	800	807
No. participants with comorbid anxiety disorder/s	144 (23)	158 (26)
No. participants with comorbid mood disorder/s	118 (19)*	277 (46)

Notes. ABS = Australian Bureau of Statistics. *p < .001.

Discussion

The data obtained challenge the assertion that anxiety patients who attend clinics are more likely to have comorbid diagnoses, particularly involving depression. The clinic profile also suggested that panic/agoraphobia patients are more strongly represented, and those with social phobia and PTSD underrepresented compared to epidemiological data. Demographic differences, apart from the female preponderance in the clinic sample, seemed attributable to the specific population profile of South Western Sydney.

In relation to comorbidity, additional anxiety disorders were as common in the clinic as in the ABS study, but persons with comorbid anxiety and depression were much less common in the clinic sample. This finding is at odds with existing research (Andrews et al., 2002; Hunt, 2000; Kessler et al., 1996; Roy-Byrne et al., 2000). Several explanations may account for the discrepancy. On the one hand, the CIDI may generate an excess of comorbid diagnoses compared to clinical assessments made by clinicians, who tend to apply a more judicious approach in assigning multiple diagnoses. The SCID, which was found to agree strongly with clinic diagnoses, allows more clinician discretion than does the CIDI. Hence it seems likely that trained clinicians reconcile overlapping phenomena and only assign an extra diagnosis of depression if the case for a second diagnosis is strong. Additionally, in cases where depression was regarded as the primary diagnosis at the clinic, patients were referred to other agencies, and thus not included as intake cases. In contrast, the ABS study would have included all cases of comorbid anxiety/depression irrespective of the salience of each from a clinical perspective. It also is possible that referral sources have become more accurate in assessing the cases most appropriate for the anxiety clinic, with depressive and other disorders being largely filtered out prior to referral. Hence, a combination of factors may have limited the number of persons with comorbid anxiety and depression from entering the clinic.

The diagnostic differences and similarities across the two samples require careful consideration. Although measurement differences could account for the discrepancies, it is noteworthy that the diagnostic profile found at the anxiety clinic corresponded closely with that of a study of anxiety clinics across Canada (Swinson, Cox, Kerr, Kuch, & Fergus, 1992), where panic/agoraphobia was also the largest category treated (30%), followed by GAD (22%), social phobia (13%), OCD (9%) and PTSD (9%). Such a trend may reflect the acuity of panic attacks and associated fears of underlying physical illness that lead sufferers to seek help more rapidly from hospitals or general practitioners. This possibility is supported by the findings of Olfson, Kessler, Berglund, and Lin (1998), which indicated that persons with panic disorder were more likely to seek help within the first year of symptom onset compared to any other anxiety, mood or addictive disorder. Growing awareness of the condition among the public and health professionals may also play a role in rapid identification and referral.

The relative underrepresentation of social phobia in the clinic compared to those identified in the community by the ABS study, although not unexpected, is of particular concern given growing evidence attesting to high levels of disability among this group (Norton et al., 1996). In support of our findings, Pollard, Henderson, Frank and Margolis (1989) reported that only 8% of a sample of 113 persons with social phobia had sought professional help. This trend is not surprising, given that avoidance and embarrassment associated with social encounters are typical of the disorder. Some data suggest that persons with social phobia, perhaps more so than other anxiety disorders, seek treatment only when comorbidity with other disorders emerges (Walker & Kjernisted, 2000). Drug and alcohol abuse has been cited as a common comorbid disorder (Lampe, Slade, Issakidis, & Andrews, 2003; Weiller et al., 1996). As such, it is possible that the clinic procedure of referring patients with a predominant drug and alcohol abuse problem for specialist treatment may have artificially lowered the number of social phobia cases identified at the clinic.

PTSD patients also appeared to be underrepresented in the clinic. Several factors might account for this trend, including the avoidance of confronting past traumatic memories characteristic of the disorder, and the availability of specific alternative treatment programs for victims of assault or refugee trauma. Nevertheless, the literature suggests that many cases of PTSD remain untreated even when specialist services are available, with specific characteristics such as severity of symptoms (Calhoun, Bosworth, Grambow, Dudley, & Beckham, 2002; Solomon, 1989), comorbidity (Bland, Newman, & Orn, 1997) and other risk factors, for example, a childhood history of sexual abuse (Rynearson, 1995) determining the likelihood of help-seeking.

Last, the higher attendance of female patients at the clinic than in the population study replicates a widely reported trend in the literature for most forms of mental disturbance (Bland et al., 1997; Leong & Zachar, 1999). Other apparent demographic differences between the two studies were readily attributable to the specific characteristics of the clinic's catchment area.

Limitations of the study design are evident. No definitive conclusion can be drawn about differences between CIDI and clinic/SCID diagnoses because the two approaches were not directly compared in each sample. Also, the clinic sample was specific to Bankstown, Sydney, whereas the epidemiological sample was drawn from multiple sites in Australia. Finally, even though there are relatively few psychiatrists and psychologists working in the area compared to most of Sydney as a whole, it was not possible to estimate how many anxiety patients were referred to these alternate treating agencies.

Conclusions

This study shows that the largest subcategories of anxiety patients attending a clinic in South Western Sydney sought help for panic/agoraphobia, followed by GAD. This represents a reversal of the order of prevalence documented in the community. Social phobia and PTSD were relatively underrepresented at the clinic. Although the findings suggest that there is a reasonable representation of subcategories of anxiety in clinic populations, there is a need to encourage underrepresented groups (those with social phobia and PTSD) to attend treatment. Comorbidity of anxiety and depression was lower than in the epidemiological study. This finding adds to concerns that anxiety disorders may be somewhat over-enumerated in epidemiological studies. Such a trend would be reversed if there were greater clarity in large-scale studies in determining whether either anxiety or depression represents the key clinical problem.