What is the seasonal distribution of community acquired pneumonia over time? A systematic review

Background: Community-acquired pneumonia (CAP) is a growing public health concern in many developed countries including Australia. CAP account for an estimated two percent of all overnight hospital admissions in Australia. Despite the significant burden on the Australian healthcare system and the high level of morbidity and mortality associated with CAP, there has been a paucity of research on the incidence of disease in this country, particularly in relation to seasonal variation of emergency department presentations and subsequent admission. Methods: The following search terms were used: community-acquired AND pneumonia AND/OR seasonal AND season AND/OR variation OR differences. The limits used for the search terms included: All Adult ; the years 1948 to current or 1948 to week 1 May 2012, (depending on the database); English language; and with full text. The databases searched included MEDLINE, Embase and CINAHL. Results: Distinct seasonal patterns in the occurrence of CAP were observed: 34 of CAP admissions occurred in spring; 18 in autumn; 26 in winter; and 22 in summer (p= 0.036). Hospital admissions for CAP were significantly higher in the winter and spring (p=