Seasonal pattern of early mortality and infectious complications in liver transplant recipients

Seasonal variation has been documented in the frequency and attributable mortality of a number of medical illnesses and infections in the nontransplantation setting. Whether similar trends exist in transplant recipients is not known. Seasonal rates of overall and early mortality and contributory variables stratified by season were assessed in 190 consecutive liver transplant recipients who underwent transplantation over a 10-year period. The frequency of infectious complications and rejection was also assessed and stratified by season of transplantation. Early (deaths occurring in the first year posttransplantation), but not overall, mortality correlated significantly with seasonality. Of patients with early mortality, 43% (13 of 30 patients) died in winter; 23% (7 of 30 patients), in spring; 13% (4 of 30 patients), in summer; and 20% (6 of 30 patients), in fall. The frequency of deaths in winter was significantly greater than for all other seasons (P = .022). The high wintertime mortality could not be explained by previously recognized risk factors portending a poor outcome, e.g., United Network for Organ Sharing status, Child-Pugh score, surgical time, blood loss, pretransplantation and posttransplantation dialysis, infections, rejection, or increased immunosuppression. Strong trends toward a higher rate of cytomegalovirus disease in patients who underwent transplantation in fall (P = .09) and bacterial infections in those who underwent transplantation in winter were documented (P = .09). There was no correlation between seasonality and rejection. Early mortality in winter in liver transplant recipients was significantly greater than if the deaths were totally random. Whether the seasonal clustering of deaths and infections is triggered by respiratory viruses, yet unrecognized viruses, or unknown exogenous factors remains to be determined.