Psychiatric comorbidity and pharmacological treatment patterns among patients presenting with insomnia - An assessment of office-based encounters in the USA in 1995 and 1996

Background: Epidemiological studies reveal that approximately one-third of the US adult population experiences insomnia, and that nearly 10% report it to be a serious or chronic problem. Little is known as to the extent of ph ysician diagnosis of the underlying illness, or the prescribing of pharmaco therapy for this complaint. Objectives: To discern among US ambulatory patients presenting with insomni a as either the primary complaint, or as one of several reasons for request ing a physician-patient office-based encounter (visit), the percentage of s aid encounters wherein: (i) a diagnosis of insomnia was recorded [Internati onal CIassification of Diseases, 9th Revision, Clinical Modification (ICD-9 -CM) codes 307.41, 307.42, 307.49, 780.50, 780.52, 780.55, 780.56, 780.59]; (ii) a diagnosis of a concomitant mental disorder (non-sleep-related) was recorded (ICD-9-CM codes 290-307.39, 307.5-319); (iii) a diagnosis of a dep ressive illness was recorded (ICD-9-CM codes 296.2-296.36, 300.4, 311); (iv ) a regimen of a hypnosedative was continued or prescribed [National Drug C ode (NDC) 0626]; (v) a regimen of antidepressant pharmacotherapy was contin ued or prescribed (NDC 0630); and (vi) a diagnosis of depression was record ed and a regimen of antidepressant pharmacotherapy was continued or prescri bed. Methods: Data from the National Ambulatory Medical Care Survey for the year s 1995 and 1996, for adults aged 18 years or older, were utilised for this analysis. Results: In the time-frame 1995 to 1996, an annualised mean of 3 027 312 pa tients presented with a complaint of insomnia as one of three reasons recor ded for requesting an office-based visit. Insomnia was the primary reason f or an office-based visit in 35.1% (1 061 396) of these patients. The majori ty of these patients were female (55.6%), White (66.2%), and had a mean age of 53.2 years (+/- 16.8 years). Compared with patients presenting with ins omnia as one of three reasons for the visit, a higher proportion of patient s presenting with insomnia as the primary reason for the visit were diagnos ed with insomnia (18.8%), diagnosed with a non-sleep-related mental disorde r (57.4%), diagnosed with depression (31.7%), prescribed or continuing a re gimen of hypnosedative pharmacotherapy (16.1%), prescribed or continuing a regimen of antidepressant pharmacotherapy (48.3%), or diagnosed with depres sion and prescribed or continuing a regimen of antidepressant pharmacothera py (27.8%). Only 15.8% of the reporting physicians were psychiatric special ists. Conclusions: Our findings indicate that fewer than 5% of US adults with ins omnia reported visiting a physician specifically for this problem. The resu lts suggest that insomnia is multifactorial in origin, with the majority of patients having been diagnosed with a non-sleep-related mental disorder, p rimarily depression.