High incidence of pyelonephritis-related hospitalization after renal transplant
Renal transplant recipients have a high incidence of hospitalization due to pyelonephritis, according to a Danish population-based cohort study.
The incidence rate (IR) of first-time hospitalization for pyelonephritis among renal transplant recipients was 18.5 (95 percent confidence interval [CI], 16.4-20.9) and 0.26 (95 percent CI, 0.21-0.31) among age and gender matched population controls (up to 19 controls per transplant recipient) per 1,000 person-years follow-up. [BMC Infect Dis 2016;16:264]
After adjusting for age, gender, calendar periods, and Charlson comorbidity index (CCI) score, the risk of pyelonephritis was higher than that of population controls (incidence rate ratio [IRR], 63.9, 95 percent CI, 50.2-81.3). Renal transplant patients without comorbidities (except end-stage renal disease [ESRD]) also had a higher risk of pyelonephritis (IRR, 73.5, 95 percent CI, 56.1-96.3) compared to controls without comorbidities.
The highest risk of pyelonephritis appeared to be in the first 6 months after transplant (31.8 percent; IR, 69.9 per 1,000 person-years follow-up, 95 percent CI, 56.4-86.7).
Among the risk factors for first-time hospitalization for pyelonephritis in transplant recipients were gender (females had a higher risk), high CCI score, hypertensive or polycystic kidney disease, and chronic interstitial nephritis.
Ninety-day mortality after hospitalization for pyelonephritis was similar between transplant recipients and controls (1.5 vs 1.8 percent, respectively). Pyelonephritis was also associated with a 45 percent increased risk of graft loss and death (IRR, 1.45, 95 percent CI, 1.19-1.77).
“Our findings confirm that pyelonephritis is a common cause of hospitalization after renal transplantation. In addition, we found that the combined risk of graft loss and death was increased by 45 percent in renal transplant recipients following an episode of pyelonephritis compared to those with no admission due to pyelonephritis,” said the study authors, who suggested that the results could potentially help improve prognosis in transplant recipients by reducing pyelonephritis risk.
To determine the prevalence and risk factors for pyelonephritis in renal transplant patients and its subsequent impact on graft survival and mortality in this group, researchers conducted a nationwide, population-based study between 1990 and 2009. Using data from the Danish Nephrology Registry (DNR) which contained information on 4,062 renal transplant recipients in the study time frame, researchers recruited individuals aged ≥16 years who had undergone renal transplantation after 1 January 1990. The Danish National Registry of Patients (DNRP) was used to obtain patient hospitalization data.
The final number of participants was 2,656 renal transplant recipients (14,121 person years follow-up) and 49,226 matched population controls (447,976 person years follow-up) who were followed-up for a median 4.3 and 8.7 years, respectively. First-time hospitalization for pyelonephritis occurred in 261 transplant recipients (9.8 percent) and 115 controls (0.2 percent).