Original Contribution Psychiatric Hospitalizations in a Cohort of Danish Polio Patients

Although previous polio infection remains a considerable cause of long-term morbidity worldwide, few studies have examined the psychiatric consequences of poliomyelitis. The authors followed 4,660 polio patients hospital-ized at the primary infectious disease hospital in Copenhagen, Denmark, between 1922 and 1954 as well as 19,017 age- and gender-matched Danes for psychiatric hospitalizations from January 1, 1977, to December 31, 1993. Incidence rates of all psychiatric disorders combined and of separate diagnostic groups of psychiatric dis-eases in the two cohorts were compared, yielding the incidence rate ratio, a measure of relative risk. Overall, polio patients had a 40 % increased risk of being hospitalized for a psychiatric disorder (incidence rate ratio 1.43, 95% confidence interval: 1.23, 1.66). Apparently, the overall increased risk of psychiatric hospitalizations could not be con-fined to specific groups of psychiatric disorders but seemed to be explained by slightly increased risks of several different disorders, especially milder psychiatric disorders. Finally, psychiatric morbidity did not differ between paralytic and nonparalytic polio patients. History of hospitalization for polio might be associated with subsequent risk of hospitalization for psychiatric disorders. The underlying mechanism for this association remains uncertain. Denmark; hospitalization; mental disorders; poliomyelitis Abbreviations: CI, confidence interval; ICD-8, International Classification of Diseases, Eighth Revision; IRR, incidence rate ratio. Chronic and life-threatening diseases are known to be ac