Admissions to a U.K. teaching hospital with nonnecrotizing lower limb cellulitis show a marked seasonal variation

Conflicts of interest: none declared. Sir, Nonnecrotizing cellulitis of the leg is a common cutaneous bacterial infection that accounts for 3% of emergency consultations in the U.K.1 and frequently requires hospital admission. A number of aetiological factors have been described, including chronic venous insufficiency, oedema, obesity, tinea pedis, leg ulceration, dermatoses and onychomycosis.2–5 As part of a programme to manage this condition more effectively between primary and secondary care we reviewed data on all admissions to a teaching hospital for nonnecrotizing lower limb cellulitis over a 3‐year period. We observed a marked seasonal variation in admissions for this common condition. We included all patients admitted for nonnecrotizing cellulitis of the lower limbs between 1 April 2004 and 1 April 2007 to Addenbrooke’s Hospital Cambridge (Cambridge University NHS Foundation Trust). The diagnosis was identified retrospectively by examination of the hospital computer database for primary diagnosis code (as per ICD10 classification) of admitting episode. A total of 1094 cases of lower limb cellulitis were identified. We carried out a comparison of the actual number of admissions by month with that predicted assuming no seasonal variation (average monthly admissions corrected for number of days per month). The null hypothesis that there was no relationship between month of the year and number of admissions was analysed by χ2 comparison. This gave a χ2 value of 43·12 with 11 degrees of freedom, P <0·001, hence we rejected the null hypothesis. A visual inspection of the data (Fig. 1) shows a clear seasonal trend in admissions with the six highest admission months being April‐‐September, peaking in May with a total of 123 admissions for this month over the 3‐year period and falling to a minimum of 63 for February. We conclude that admissions for nonnecrotizing cellulitis in East Anglia are markedly increased in late spring and summer months compared with the rest of the year.