Psychiatric Morbidity in Patients With Psoriasis

Psoriasis is a common immune-mediated papulosquamous skin disease with a generally chronic course. Impairments in quality of life (QOL) and psychological morbidity in the form of anxiety and depression have been reported.¹ Because psoriasis is not known to directly affect the central nervous system, the associated psychiatric morbidity is likely caused by the complex interplay of the stress, physical discomfort, and possible disfigurement inherent to psoriasis, as well as the emotional response to the condition mediated by the patient’s personality, emotional and cognitive state, and other social factors (eg, self-stigma and perceived stigma, lack of knowledge about the illness in the patient and in the community and family, lack of resources and support).² Because a variety of methodologies have been used in research on the association of psoriasis with psychiatric morbidity, it is not easy to compare findings. Most studies have assessed psychiatric symptoms rather than findings from psychiatric diagnostic instruments.³ The diagnosis of psychiatric disorders in patients with psoriasis rather than focusing on symptoms alone is likely to be more useful in generating scientific epidemiologic data and also would serve as a guide in making treatment and policy decisions. Validated clinician-rated instruments are useful in generating these data. However, psychiatric diagnoses are often missed by dermatologists, which may have an adverse impact on eventual outcomes in psoriasis patients.^4,5 Patient-assessed diagnostic instruments may help dermatologists overcome this problem.

This study investigated the prevalence and determinants of psychiatric disorders in a cohort of psoriasis patients in North India using both patient self-assessment and clinician-administered instruments.

Methods

Study Participants

The study was conducted from January 2013 to November 2013 at the Postgraduate Institute of Medical Education and Research, a tertiary-level teaching hospital in Chandigarh, India, which serves the population of a large geographic area in North India. Clearance for this study was obtained from the institute ethics committee.

Patients with chronic plaque psoriasis who presented consecutively to the outpatient clinic of the Departments of Dermatology, Venereology, and Leprology during the study period were approached for participation. Written informed consent was obtained from all participants. Inclusion criteria were the ability to read the self-assessment questionnaires, and no financial compensation was offered for inclusion in the study. Patients with psoriatic arthritis as well as erythrodermic and pustular variants of psoriasis were excluded. Exclusion criteria also included patients with known diabetes mellitus, cardiovascular disease, chronic respiratory ailments, or other notable systemic comorbidities; however, patients did not undergo biochemical testing.

Assessments

A 2-stage methodology was employed. In the first stage of the assessment, sociodemographic and clinical data were recorded. Thereafter, psychiatric symptoms and morbidity were assessed using the patient health questionnaire (PHQ).⁶ Quality of life was assessed using the dermatology life quality index (DLQI).⁷ Both tools were based on patient self-assessment. Study participants could seek assistance from the clinician in completing the questionnaires, if needed. Psoriasis severity was evaluated by the clinician using the psoriasis area severity index (PASI) score.⁸

In the second stage of the assessment, participants underwent subsequent evaluation by a psychiatrist who was blinded to the results of the first assessments. All participants were screened using the Mini international neuropsychiatric interview (MINI)⁹ and a formal psychiatric diagnosis was made. In subsequent analyses, we considered psychiatric diagnoses as generated with MINI as the gold standard against which other results were compared.

A participant was considered positive for psychiatric morbidity if he/she was positive for at least 1 PHQ or MINI diagnosis.

To assess for concordance between the 2 diagnostic instruments, the following diagnostic groups were compared against each other: (1) MINI depressive disorders (DDs)(ie, major depressive episode, current and recurrent; dysthymia) versus PHQ depressive disorders (ie, major DDs and other DDs); (2) MINI anxiety disorders (ie, panic disorder and generalized anxiety disorder) versus PHQ anxiety disorders (ie, panic syndrome and other anxiety syndromes); (3) MINI alcohol abuse (ie, alcohol dependence and abuse) versus PHQ alcohol abuse; (4) comorbid disorders if more than 1 diagnosis was made; and (5) any positive score on the MINI suicide module with a response other than not at all on PHQ depression module item 2(i), which deals with thoughts of self-harm and wishing that one was dead. The MINI depressive disorders and PHQ depressive disorders indicate the presence of a clinically significant depressive state and a need for assessment and treatment.

The PHQ can be used to diagnose somatoform disorders, while the MINI cannot be used. Because the somatoform disorders diagnosed were few in number and comorbid with DDs (n=3) and anxiety disorders (n=1), we included these cases with DDs and anxiety disorders, respectively, for purposes of statistical analysis. All data were analyzed using SPSS software.