Prevalence of Psychiatric Disorders among Patients Investigated for Occupational Asthma. An Overlooked Differential Diagnosis?

Abstract

Up to one-third of patients assessed for occupational asthma (OA) do not receive a diagnosis of OA or any other medical disorder. Although several differential diagnoses are considered (e.g., rhinitis, chronic obstructive pulmonary disease), psychiatric disorders (many with somatic complaints that mimic asthma) are rarely considered or assessed. To assess the prevalence of psychiatric disorders (mood and anxiety disorders and hypochondriasis) in patients suspected of having OA, and whether psychiatric morbidity increases the risk of not receiving any medical diagnosis. A total of 219 consecutive patients (57% male; mean age, 41.8 ± 11.1 yr) underwent sociodemographic and medical history interviews on the control or specific inhalation testing day of their OA evaluation. The Primary Care Evaluation of Mental Disorders was used to assess mood and anxiety disorders, and the Whiteley Hypochondriasis Index was used to assess hypochondriasis. A total of 26% (n = 50) of patients had OA; 25% (n = 48) had asthma or work-exacerbated asthma; 14% (n = 28) had another inflammatory disorder; 13% (n = 26) had a noninflammatory disorder; and 22% (n = 44) did not receive any medical diagnosis. A total of 34% (n = 67) of patients had a psychiatric disorder: mood and anxiety disorders affected 29% (n = 57) and 24% (n = 46) of the sample, respectively, and 7% (n = 12) had scores on the Whiteley Hypochondriasis Index indicating hypochondriasis. Hypochondriasis, but not mood or anxiety disorders, was associated with an increased risk of not receiving any medical diagnosis (adjusted odds ratio, 3.92; 95% confidence interval, 1.18-13.05; P = 0.026). Psychiatric morbidity is common in this population, and hypochondriasis may account for a significant proportion of the "undiagnosable" cases of patients who present for evaluation of OA.