Screening for depressive disorders in outpatients with mild to moderate psoriasis: A study from North India

INTRODUCTION

Psoriasis is a common, chronic, papulosquamous skin disorder with a complex immune-mediated etiopathogenesis. ^[1] Depressive disorders are known to be commonly comorbid with psoriasis. ^[2] The presence of depressive disorders in psoriasis has an adverse bearing on the quality of life. ^[3],[4] However, the importance of a concomitant depressive disorder on the course and outcome of psoriasis is often underestimated and under-recognized. ^[5],[6] Thus, there is a need to to rapidly and accurately screen for depressive disorders in this population. We studied the feasibility of using the adaptation of an easily available questionnaire to rapidly screen for depressive disorders in a cohort of outpatients with psoriasis.

Materials and Methods

This study was carried out as a part of a project investigating the prevalence and determinants of common mental disorders in out patients with psoriasis. Other findings are under publication elsewhere. This study was conducted from January to November 2013 in the departments of dermatology and psychiatry at the Post Graduate Institute of Medical Education and Research, Chandigarh, India after obtaining due approval from the Institute Ethics Committee. In the first stage of the study, consecutive patients with chronic plaque psoriasis who were attending the outpatient clinic of the department of dermatology were approached for participation. Written informed consent was obtained from participants in the study. Exclusion criteria included refusal to participate in the study and inability to understand or answer the questions. Patients with an organic brain condition, psoriatic arthritis, erythroderma pustular psoriasis, diabetes, hypertension, any chronic systemic disease, or an underlying psychiatric illness were also excluded. The socio-demographic and clinical details of consenting patients were recorded. Thereafter, the dermatologist asked the participants the first four modified questions of the Patient Health Questionnaire-9 (PHQ-9), ^[7],[8],[9] a self-administered screening and diagnostic tool for major and other depressive syndromes which has been widely used and validated in various countries and languages. ^[10] The instrument was modified as follows: (a) The questions were limited to the four most important ones, decided on the basis of clinical experience, instead of nine in the original PHQ-9. (b) instead of asking "how often" they had been bothered by any of the problems listed over the last 2 weeks, the participants were asked, "if" they had been "significantly" bothered by them and the responses were marked as "yes" (Score 1) or "no" (Score 0). The scores were then added to arrive at a final score. The questionnaire as administered is presented in [Figure - 1]. Psoriasis Area Severity Index (PASI) and Dermatological Life Quality Index (DLQI), ^[11],[12] were also used for evaluation.

Figure 1: Modified questionnaire used for the study

The second stage of the study was carried out in the department of psychiatry. In this, the patients were administered the Mini International Neuropsychiatric Interview (MINI) ⁽¹³⁾ by a psychiatrist who was blinded to the earlier assessment, to generate a psychiatric diagnosis. For the purposes of this part of the study, the diagnosis of depressive disorders included major depressive episode (MDE), current and recurrent, and dysthymia. All data were later analyzed using SPSS software (Version 18.0) for Windows.

RESULTS

A total of 104 participants (79 males and 25 females) consented to be a part of this study. Evaluations with the Psoriasis Area Severity Index (PASI) and Dermatological Life Quality Index (DLQI) indicated that most patients had psoriasis of mild to moderate severity. Mean PASI and DLQI scores with standard deviations of the recruited patients were 6.67 (6.16) and 6.88 (6.15), respectively. The prevalence of depressive disorders was 39.4% (27 of 79 males and 14 of 25 females). The most frequent psychiatric diagnosis was dysthymia which was made in 22 of 27 males and 9 of 14 females. The mean scores and standard deviations on the modified questionnaire in the participants with no psychiatric diagnosis, those diagnosed with dysthymia, and those with major depressive episode were 0.73 (1.24), 2.29 (1.46), and 2.90 (1.28), respectively. Analysis of variance (ANOVA) revealed that the mean scores in the "no psychiatric diagnosis" group were significantly different from those of both the second and third groups (P < 0.05 in both cases). The mean scores in the dysthymia and major depressive episode groups were not found to be significantly different (P = 0.44).

[Table - 1] presents the results of the performance of the modified questionnaire based on the first four questions of PHQ-9 in detecting depressive disorders at different cut-off points. A receiver operating characteristic (ROC) analysis revealed an area under the curve (AUC) of 0.81 (SE = 0.04, 95% confidence interval = 0.72-0.89).

Table 1: Sensitivity and specificity analyses at different cut-off points of the modified questionnaire

DISCUSSION

A major barrier to the diagnosis of depressive disorders in primary care is the absence of rapidly administered screening instruments ^[14] and attempts have been made to develop such short screening questionnaires. ^[15] While screening questionnaires with two or three items have acceptable sensitivity, the specificity is less than desired. ^[15] Secondly, these questionnaires have been designed to screen for major depression, whereas in our experience, dysthymic disorders are also very common and clinically relevant in the medically ill. Finally, all these questionnaires are in English and are not available in local languages. We attempted to analyze the performance of the first four items of the Hindi translation of PHQ-9 as a rapid, screening instrument for diagnosing depressive disorders. We chose these items for this study because item numbers 1, 2, and 4 are reflective of the major criteria for the diagnosis of major depressive episode as per the ICD-10 and item number 3 inquires into sleep disturbances which are common in patients with depressive disorders, as well as being a criterion for diagnosis of major depressive episode. ^[16] In our experience, these four problems are most commonly expressed by patients with depressive disorders in our region. Our study population was predominantly composed of subjects with mild to moderate psoriasis in various stages of the disease and treatment. We believe our study population is reflective of the majority of subjects who need to be assessed for depressive disorders. We found that the administration of this questionnaire was useful in screening and took only about a minute to administer. It could be easily administered by the dermatologist and was easily understood by patients. The yes/no answer format reduced ambiguity and the time taken to administer the questionnaire.

The ROC analysis and the area under the curve (AUC) indicated good accuracy of the instrument in the detection of depressive disorders in this population. ^[17] A cut-off score of 2 or more provided optimum sensitivity and specificity (0.70 and 0.76, respectively). Patients who score more than 2 should be evaluated more thoroughly and managed accordingly. Our results also indicate that the prevalence of dysthymia was more than that of major depressive episode and the severity of the two as measured by the total score on the questionnaire was similar. This is probably because of the chronic stressful nature of psoriasis and the impaired quality of life that leads to chronic depressive states and mild to moderate rather than severe and psychotic major depressive episodes. Screening for depressive disorders in primary care populations should also take cognizance of dysthymic states, which are probably common and cause comparable morbidity, rather than focusing exclusively on major depressive episodes.

We recommend that screening for depressive disorders should be an initial part of a comprehensive, multi-disciplinary management plan for patients with psoriasis.