Infection-Related Hospitalization Rates in Pediatric versus Adult Patients with End-Stage Renal Disease in the United States

Materials and Methods

Results

Discussion

Our data show that hospitalization for infection is common in incident US pediatric and adult patients with ESRD, with 12-mo cumulative incidence between 25 and 31% for both groups. Previous studies reported IH rates in adults with ESRD to vary between 13 and 35% (5–8,16). The IH rates for this national sample of 332,442 adult incident dialysis patients are similar to the 35% reported for a contemporary US adult HD cohort (6). Our IH rate of 39.8% over 3 yr in a national sample of 31,663 adult KTx patients is somewhat higher than the 18.5% reported in a single-center study of 220 adult KTx patients who received a transplant between 1990 and 1999 (8). However, infection also was the major cause of hospitalization for those study patients. Although the USRDS database pertains to a national population, it is unclear how IH rates would have been affected by the inclusion of excluded patients. Both old age and young age are risk factors for infection in patients with ESRD, and excluded pediatric and adult dialysis patients were younger than included patients.

To our knowledge, ours is the first study to compare IH rates for both pediatric and adult US incident patients with ESRD and the first to examine IH rates by treatment modality for children with ESRD. We found variation in rates of IH by age and by ESRD modality. Adult HD patients had a 10 to 12% higher cumulative incidence of IH than did pediatric HD patients. The reason for this difference is unexplained; risk factors for infection, such as access device application, affinity of organisms for foreign materials, dialyzer membrane interaction, uremia, nasal and skin colonization with bacteria, vitamin D deficiency, and malnutrition are common to both adults and children (12–14,17). A possible explanation is that most adult patients with ESRD are treated with hemodialysis and the waiting lists for transplantation are long, whereas nearly three fourths of pediatric patients with ESRD receive a transplant within 3 yr of developing ESRD. We found little difference in the incidence of IH between adult and pediatric PD patients.

Although the rates per 1000 patient-months of access-related IH were similar for children and adults, a greater percentage of IH was due to access devices in pediatric HD patients than in adult HD patients (43 versus 27%; data not shown). Other studies have reported access-related IH incidence to range from 1.5 to 23% in adult HD patients (5,6,18). A higher percentage of pediatric patients undergo dialysis with catheters for vascular access compared with adults. For 2002, approximately 40 to 50% of adult patients with ESRD initiated dialysis with catheters compared with 78% for pediatric patients who were younger than 13 yr and 44% for those who were 13 yr and older, which may explain partially the increased incidence of IH in pediatric HD patients (19). In a retrospective cohort study of nearly 7500 adult HD patients, the use of a venous catheter for dialysis was associated with a higher incidence of death as a result of infection (3.4%) compared with use of a graft (1.2%) or a fistula (0.8%; P < 0.001) (15).

Our results show that IH rates for any infection during the first 12 mo after initiation of ESRD therapy are highest for pediatric KTx patients compared with adult KTx patients and with pediatric and adult dialysis patients. The adjusted rate of IH for pediatric KTx patients is between one-and-a-half and two times that for pediatric dialysis patients and almost twice that of adult KTx patients.

We did not break down instances of IH by type of infection because often the specific organism was unknown. The most common infection diagnoses included the specification “organism NOS.” Therefore, we were unable to classify the infection as bacterial, viral, or fungal. It is unclear how new protocols with immunosuppression for transplant patients will affect future rates. However, North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) data show that despite changes in induction and maintenance immunosuppression protocols for pediatric patients since 1987, a more recent year of transplantation is associated with increased IH (11). Similarly, although intuitively the “Fistula First” protocol for dialysis patients should reduce the rate of access infections in the future, our analysis is based on diagnosis codes that do not distinguish between access infections for catheters, fistulas, or grafts; attributing infections for KTx patients to central lines therefore also is impossible. More specific data collection is needed to assess these differences.

Few studies examine IH rates in children with ESRD. Furth et al. (20) reported hospitalization risk for 1112 prevalent pediatric ESRD patients, 44% dialysis and 54% KTx, who were aged 17 yr or younger, had growth failure (defined as >2 SD below the mean in height for age and gender), and participated in a 1990 special USRDS Pediatric Growth and Development study. Overall, 73% of patients were hospitalized during 5 yr of follow-up, and infection accounted for 53% of the hospitalizations (20). IH rates were not compared by type of dialysis modality. A retrospective study using NAPRTCS data evaluated morbidity and mortality in 1942 children, 69% PD and 31% HD, who had anemia (defined as hematocrit <33%) and initiated dialysis between 1992 and 2001 (9). Overall, 857 patients, 44% PD and 46% HD, were hospitalized within 12 mo of start of dialysis (9). At 7 to 12 mo after the start of dialysis, infection was the cause of 27% of hospitalizations for nonanemic PD patients, 28% for anemic PD patients, 3% for nonanemic HD patients, and 21% for anemic HD patients (9). Causes of IH were not examined.

A recent report from NAPRTCS compared hospitalization incidence for infection and rejection during a 2-yr period for 6701 children who received transplants between 1987 and 2000 (11). In the NAPRTCS study, the percentage of IH increased slightly overall from 38% in 1987 to 40% in 2000 (11). We found no significant variation in IH rates for pediatric KTx patients for each calendar year between 1996 and 2001. NAPRTCS is a voluntary registry, and the reporting of hospitalizations or cause of hospitalization may have been incomplete.

We found IH rates for UTI to be high for both adult and pediatric KTx patients. In the single-center study of 164 pediatric KTx patients, UTI was the most common cause of IH beyond the first 2 wk after transplantation (10). The larger NAPRTCS study of pediatric KTx patients did not report IH data by site of infection (11). In a retrospective cohort study of 28,942 adult Medicare KTx patients in the USRDS database between January 1, 1996, and July 31, 2000, 28% had claims for UTI during a hospitalization (21). UTI was coded as the primary discharge diagnosis in 25% of the 8812 KTx patients with inpatient claims for it.

Deaths during IH were more frequent for dialysis patients than for KTx patients in both the adult and pediatric patient groups. For pediatric dialysis patients, deaths during IH were more frequent for HD than for PD patients. In the pediatric dialysis study by Warady and Ho (9), infection was the primary cause of death in 21% of anemic patients and 18% of nonanemic patients. However, infection-related deaths were not analyzed by hospitalization status, cause of hospitalization at the time of death, or type of dialysis. Infection as a major cause of death among pediatric patients with ESRD is well documented (1–3,9,20,22–24). However, we could not find previous pediatric studies that evaluated patients with ESRD for IH deaths or analyzed infection-related deaths by type of treatment modality. For adult dialysis patients, deaths during IH were more frequent in PD than in HD patients. A study from the 1990s compared cause of death among a large national sample of prevalent adult dialysis patients using USRDS data and found a 40% higher infection-related death rate for PD patients (4.8 per 100 patient-years) compared with HD patients (3.4 per 100 patient-years) (25). Although the findings are similar to ours, their analysis was not limited to deaths during IH.

A potential limitation of our study is that we examined IH using only ICD-9-CM codes that listed infection as the primary diagnosis for hospitalization. This limitation is offset, however, by the fact that the national Medicare data contain relatively complete hospitalization records. We relied on information that was contained in the CMS Death Notification (CMS-2746) for cause of death; these forms may contain some inaccuracies. The criteria for admission to hospital may differ between pediatric and adult patients. Finally, we did not analyze for adequacy of dialysis. Despite the limitations, a large national study such as this one may be the only way to assess the complications that we address.

Conclusion

Our study of incident US patients with ESRD shows that pediatric patients have a high burden of hospitalizations from infection. Compared with adults, pediatric patients have fewer IH on HD and more IH after KTx. These results indicate opportunity for improvement in reducing infection and IH rates in patients with ESRD. In particular, pediatric KTx patients require more infection surveillance and likely require prolonged prophylactic antibiotic treatment after transplantation. A focus of future research should include analysis of secondary infections during hospitalizations in patients with ESRD and differences in IH death rates for PD and HD patients.

Disclosures

None.