Comorbidity of hospital-treated psychiatric and physical disorders with special reference to schizophrenia: a 28 year follow-up of the 1966 Northern Finland general population birth cohort

We studied the comorbidity of psychiatric and physical disorders in a sample (n = 11017) from the unselected, general population, Northern Finland 1966 Birth Cohort. During the period 1982–1994, hospital-treated psychiatric patients were more likely than people without psychiatric diagnoses to have been treated for physical disease in hospital wards, 298 out of 387 (77.0%) vs 6687 out of 10 630 (62.9%) (OR = 2.0, 95% CI = 1.6−2.5). Injuries, poisonings and indefinite symptoms were a more common reason for hospital treatment in people with schizophrenia or other psychiatric disorder as compared with people without a psychiatric disorder. Men with psychiatric disorder had more than a 50-fold risk for poisoning by psychotropic drugs (OR = 52.6, 95% CI = 27.7−99.8), women with psychiatric disorder a 20-fold risk (OR = 19.0, 95% CI = 9.5–38.1) and schizophrenics more than a 30-fold risk (OR = 37.5, 95% CI = 19.1–73.8). Men with psychiatric disorders were more commonly hospitalised for a variety of gastrointestinal disorders and circulatory diseases (OR = 2.3, 95% CI = 1.2–4.4), as compared with men with no psychiatric disorder. Respiratory diseases (OR = 2.2, 95% CI = 1.2–4.2), vertebral column disorders (OR = 4.2, 95% CI = 1.8–9.9), gynaecological disorders (OR = 2.1, 95% CI = 1.2–3.6) and induced abortions (OR = 1.8, 95% CI = 1.2–2.7) were more prevalent in women with psychiatric disorder than in other women. Epilepsy was strongly associated with schizophrenia (OR = 11.1, 95% CI = 4.0–31.6). Nervous and sensory organ diseases in general (OR = 2.5, 95% CI = 1.1–5.8) and inflammatory diseases of the bowel (OR = 12.8, 95% CI = 3.8–42.7) were also overrepresented in schizophrenia when compared with people without a psychiatric disorder. Our results indicate that physicians must be alert for psychiatric disorder, and mental health professionals must be aware of the considerable physical morbidity in their patients.