Long-term survival and clinical forms in the acute phase of Chikungunya virus infection in older Caribbeans

Objective To investigate whether the long-term survival in elderly patients with prior Chikungunya virus infection (CVI) is associated with the clinical form presented in the acute phase, as defined by the WHO classification. Methods Retrospective cohort study performed in Martinique University Hospitals. Patients who attended the emergency department for suspected CVI, and who had a positive biological diagnosis of CVI by reverse transcription-polymerase chain reaction on a plasma sample between 10 January and 31 December 2014 were eligible for inclusion. Time-to-death was the primary outcome. The independent relationship between clinical forms and time-to-death was analysed using a Cox model. Results In total, 268 patients were included. Mean age was 80 +/- 8 years, 53% were women. Median length of follow-up was 28 months (range: 0-39). During follow-up, 53 (19.8%) patients died. Median survival time was 13.2 months (range: 0-33.6). At the end of follow-up, death rates were 4.6% for acute clinical cases, 19.0% for atypical cases, 19.2% for severe acute cases and 23.5% for unclassifiable cases. By multivariable analysis, the clinical form of CVI at admission was found to be independently associated with long-term survival (atypical form: HR = 2.38; 95% CI = 2.15-2.62; severe acute form: HR = 2.40; 95% CI = 2.17-2.64; unclassifiable form: HR = 2.28; 95% CI = 2.06-2.51). Conclusion The clinical form at presentation with CVI has a significant impact on long-term survival. Management of CVI patients should be tailored according to their clinical form at admission.