Duration of untreated symptoms in common mental disorders: association with outcomes: International study

Studies have assessed the association between a longer durationof untreated symptoms and outcome for psychoses in specialistcare. We investigated the effect of longer duration on theoutcome of common psychiatric disorders in primary care, wheremost patients are treated. Patients presenting to primary carefor new episodes in 10 countries were recruited into a prospectivecohort study. Information on duration of untreated symptomsand psychosocial status was collected for 351 individuals usingstandardised instruments and this was repeated 1 year later.At 1-year follow-up, longer duration was associated with worsepsychiatric outcome even after controlling for potential confounders.

INTRODUCTION

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INTRODUCTION

Studies on the duration of untreated symptoms focus on timeto admission for severe mental illness such as schizophreniaand affective psychosis in Europe, Australasia and North America,rather than on common mental disorders in primary care (Craig et al, 2000;Drake et al, 2000; McGorry, 2000). The longer depression,anxiety and somatic disorders last, the worse the responseto appropriate intervention: inadequacy of treatment leadingto symptom persistence may be one reason. The kindling hypothesis suggests that longer waits for treatment may also contribute (Kendler et al, 2000).

METHOD

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METHOD

We investigated the effect of duration of untreated symptomson 1-year outcome in primary care, using data from the 1990-1993World Health Organization Collaboration Study of PsychologicalProblems in General Health Care (Ustun & Sartorius, 1995).Data were available for Ankara, Athens, Bangalore, Groningen,Ibadan, Manchester, Rio de Janeiro, Santiago, Seattle and Verona. Overall study methods are described elsewhere (Sartorius et al, 1993;Ustun & Sartorius, 1995). Studies of duration of untreatedpsychosis indicated that up to 250 participants were requiredto have an 80% chance of detecting a statistically significantresult at the 95% level (Craig et al, 2000; Drake et al, 2000).

We focused on overall psychiatric morbidity as our outcome,because patients in primary care are more likely to have amixture of depression, anxiety and somatoform symptoms thandiscrete syndromes. We analysed psychiatric outcome as a continuousvariable, instead of dichotomously (e.g. caseness), to obtainmore information on severity, including subclinical symptoms.

We screened patients aged between 16 and 65 years who had notvisited the clinic in the previous 3 months, using the 12-itemGeneral Health Questionnaire (GHQ; Goldberg & Williams, 1988).A stratified random sample of the study population (weightedtowards higher GHQ scorers) were then interviewed, using theprimary healthcare version of the Composite International Diagnostic Interview (CIDI-PHC; Robins et al, 1988; Sartorius et al, 1993).This included the Pathways to Care Interview to record theonset and duration of presenting symptoms (depressive, anxiousor somatic); whether this was the initial visit for this problem;the profession of each person consulted for those symptoms;and the main treatment offered at each step. We calculatedthe duration of untreated symptoms by subtracting the timefrom first seeking treatment in any setting and arriving atthe participating clinic (duration of pathway in treatment)from the total duration of presenting symptoms. We only includedpeople whose current presentation was their initial visit tothe participating clinic for this problem. Duration of untreatedsymptoms was assessed in weeks; zero meant symptoms had lastedless than a week.

We used the CIDI-PHC sections on somatisation, anxiety, depression, hypochondriasis and neurasthenia to measure psychiatric morbidity.Medically explained and unexplained somatic symptoms were countedusing a flow chart to establish aetiology (Robins et al, 1988).We assessed disability using the Groningen Social DisabilitySchedule (GSDS), a semi-structured interview that considerslocal norms (Wiersma et al, 1990).

At baseline, the family physician completed a questionnaireon the presence of psychiatric disorder and any treatment offered.All patients with significant psychological problems, and a20% random sample of `non-cases', were contacted for 12-monthfollow-up. Bangalore and Seattle followed up every patient.We repeated the CIDI-PHC and collected information on visitsto the participating clinic or other clinics and any hospitaladmissions, irrespective of diagnosis, during the interveningyear.

The interviewer-observer reliability coefficient for the CIDI-PHC (including the Pathways to Care Interview) was 0.92, and 0.85for the GSDS (Sartorius et al, 1993).

We restricted our analysis to patients who had not visited thepractice previously for their presenting problem and who hadan ICD-10 (World Health Organization, 1992) psychiatric diagnosis,as determined by the CIDI-PHC. We excluded patients with non-psychiatricpresentations such as visits for family planning or antenatalcare.

RESULTS

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RESULTS

In all, 3321 patients completed the baseline interview, of whom2767 were eligible for follow-up. Details of duration of untreatedsymptoms were available for 2579 people (93%). Of these, 1791(70%) were successfully followed-up.

Those who had not previously visited the participating practicefor their presenting problem numbered 900, of whom 351 metour remaining criteria of reason for presentation and psychiatriccaseness. The majority had depression (n=210); 73% were womenor girls (n=256); 81.9% had an educational level of less thangrade 12 (usually age 18 years) (n=290); 40.7% were single(n=143); and 21.4% were unemployed (n=75). Age ranged from15 to 50 years with a mean of 37.7 years (s.d.=12.9).

Duration of untreated symptoms was skewed, with a mean of 19.1weeks (s.d.=74.1) and a median of 1. We normalised the durationby taking the logarithm of the base, rather than dichotomisingor dividing into quintiles, to maximise power. We added oneto each value before transformation because of zeros (Kirkwood, 1992).The mean was 0.57 (s.d.=0.67).

We obtained information on health service use for 317 participants. Patients averaged five visits to the participating clinic andthree to other clinics; 12% (n=41) had been admitted to hospitalat least once.

On multiple regression, the duration of untreated symptoms showeda significant association with overall psychiatric symptoms1 year later (B=3.61, s.e.=1.60, P=0.02), as did initial psychiatric symptom count, older age, lower educational levels, medicallyunexplained somatic symptoms, and visits to the participatingclinic (see data supplement to the online version of this paperfor results on all variables).

The duration of untreated symptoms also showed an associationwith anxiety symptoms (B=0.46, s.e.=0.18, P=0.02) and depression (B=0.97, s.e.=0.49, P=0.05), using the same model. There was no statistically significant association when using untransformedduration of symptoms (B=0.01, s.e.=0.02, P=0.37).

DISCUSSION

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DISCUSSION

The outcome and response to treatment for common psychologicaldisorders such as depression and anxiety are inversely proportionalto their chronicity (Seivewright et al, 1998. One explanationis that inadequate intervention leads to persistence of symptoms,and collaboration between specialists and family practitionerscan help address this (Andrews, 2001; Roy-Byrne & Wagner, 2004). We suggest another explanation, i.e. longer waits for treatment.This association is modest, but still significant, after controllingfor other variables including demographics, centre attendedand initial severity of symptoms (see online data supplement).

These results support the kindling hypothesis of depression (Kendler et al, 2000), which has parallels with the criticalperiod hypothesis in early psychosis (Birchwood et al, 1998).The association between depressive episodes and adverse lifeevents weakens with successive illnesses, suggesting biologicalor psychological adaptation so that psychosocial precipitantsare no longer necessary for relapse.

Limitations include our demonstration of only an associationbetween duration of untreated symptoms and subsequent psychiatricmorbidity, not direct causation. Furthermore, our analysismay have been confounded by variables for which we were unableto control. We considered new episodes of care and not necessarilyfirst presentations of an illness. There may have been selectionbias, as patients with a short duration may have improved and never sought care (McGorry, 2000). Depression or anxiety maybe harder to recognise than psychosis, and we did not get corroborationfrom family members. Data were collected a decade ago, andso may be less applicable now. However, it is unethical tocollect further data, with the consequent cost and inconvenience to patients, without first analysing available datasets.

Our results provide a wider perspective on the duration of untreated symptoms. Research on the effects of such duration in psychosisis conflicting. Explanations have included differences in demographic characteristics, diagnostic criteria, measures of onset (firstsymptom or full syndrome), treatment definition (medicationor hospital admission), outcome measures and follow-up periods.Studies that use transformation to normalise the positive skewof duration tend to show an association with outcome in contrastto those that do not (Norman et al, 2005). This supports ournegative finding, and that of others, when using untransformedduration of symptoms (Drake et al, 2000).

ACKNOWLEDGMENTS

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ACKNOWLEDGMENTS

Anita Scott and Jennifer Denney were funded by the Nova ScotiaHealth Research Foundation.

REFERENCES

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