Incidence and mortality rates of varicella among end stage renal disease (ESRD) patients in Singapore General Hospital, a 12-year review

BACKGROUND End stage renal disease (ESRD)/ end stage renal failure (ESRF) is on the rise globally and especially in Singapore. Varicella or chickenpox is not uncommon among adults especially ESRD/ESRF patients. It has been reported to cause complications and even death among immunocompetent adults. METHODS A retrospective data collection on patients with varicella infection and ESRD in Singapore General Hospital (SGH) from the year 2005 to 2016 was performed. Continuous data and categorical data were summarized as median (range) and count (%) respectively. The association of health care utilization (total length of hospital stay, readmission related to varicella, intensive care unit admission) and mortality with complication due to varicella were tested using chi-square and Mann-Whitney test for categorical and continuous outcomes respectively. RESULTS Sixty-six patients with ESRD developed varicella during the study period (2005-2016). The case incidence rates for varicella among ESRD ranges from 97 to 267 per 100,000 populations with ESRD yearly. There were 9 deaths (13.6%). Mortality was higher among the ESRD patients with one or more varicella complications compared to patients without complications ((25% vs 7.1%, 95% CI for difference: - 1.1%, 36.9%, p = .063). Likewise, utilisation of intensive or high dependency units were higher among patients with complications compared to those without (20.8% vs 2.4%, 95% CI for difference: 1.6%, 35.3%, p = .012). Length of stay was twice as long in the group with complications compared to patients without (median (IQR) days: 14 (8, 21) vs 7 (5, 14), p = .065), although it did not reach statistical significance. CONCLUSIONS Varicella is associated with high morbidity and significant mortality rate in ESRD patients. Varicella vaccination is recommended for seronegative ESRD patients.