TY - JOUR T1 - Prevalence of comorbid psychiatric illness and substance misuse in primary care in England and Wales JF - Journal of Epidemiology and Community Health JO - J Epidemiol Community Health SP - 1036 LP - 1041 DO - 10.1136/jech.2003.017384 VL - 58 IS - 12 AU - Martin Frisher AU - Juliet Collins AU - David Millson AU - Ilana Crome AU - Peter Croft Y1 - 2004/12/01 UR - http://jech.bmj.com/content/58/12/1036.abstract N2 - Study objective: To estimate the annual period prevalence of co-occurring psychiatric illness and substance misuse among patients in primary care. Design: Analysis of the general practice research database. Setting: England and Wales, 1993–1998. Participants: Registered patients at 230 general practices representing 3.1% of the population. A comorbid case was defined as one with both a psychiatric diagnosis and substance misuse diagnosis (not including alcohol or tobacco) within a calendar year. A potentially chronic comorbid case was one that met this definition and, in addition, was treated in subsequent years for either a psychiatric condition or substance misuse. Main results: The annual period prevalence of comorbidity increased from 50/100 000 patient years of exposure (PYE) to 80/100 000 PYE, an increase of 62% during the study period. Rates of comorbid psychoses, comorbid schizophrenia, and comorbid paranoia increased by 147%, 128%, and 144%. The average age of comorbid cases decreased from 38 years to 34 years. Over 80% of comorbid cases were newly diagnosed in each study year, although many are treated in subsequent years for either psychiatric illness or substance misuse. Conclusions: This study provides data on the nature and extent of comorbidity in primary care in England and Wales. As the comorbidity rate is increasing by about 10% each year, and as comorbid cases are becoming younger, it is probable that the comorbidity rate will have increased beyond the study end point. ER -