Decreased risk of acute appendicitis in patients with schizophrenia or manic-depressive psychosis

The present study tests the hypothesis of a negative association between pa tients with schizophrenia, manic-depressive psychosis and acute appendiciti s. Using the nation-wide Danish case registers the occurrence of acute appendi citis among up to 20,402 inpatients with schizophrenia and up to 10,281 inp atients with manic-depressive psychosis and ten individually matched contro l persons for each psychiatric patient was investigated. A case-control and follow-up design was applied. Persons who developed schizophrenia had a significantly decreased relative risk of acute appendicitis of 0.49 before and of 0.59 after first psychiatr ic admission. Similarly the occurrence of manic-depressive psychosis was as sociated with a decreased relative risk of acute appendicitis of 0.50 befor e and of 0.70 after first psychiatric admission. One or more unknown factors inversely affect the risk for the subsequent de velopment of psychoses and acute appendicitis. Further studies of this rela tionship may help to clarify etiological or pathophysiological aspects of s chizophrenia and manic-depressive psychosis, (C) 2001 Elsevier Science B.V. All rights reserved.