COAGULASE-NEGATIVE STAPHYLOCOCCAL BACTEREMIA AMONG VERY-LOW-BIRTH-WEIGHT INFANTS - RELATION TO ADMISSION ILLNESS SEVERITY, RESOURCE USE, AND OUTCOME

Objective. To examine the impact of admission-day illness severity on nosocomial bacteremia risk after consideration of traditional risk det erminants such as birth weight and length of stay. Methods. The hospit al courses for 302 consecutive very low birth weight (less than 1500 g ) infants admitted to two neonatal intensive care units were examined for the occurrence of nosocomial coagulase-negative staphylococcal bac teremia. Using both cumulative incidence and incidence density as meas ures of bacteremia risk, we explored the relation between illness seve rity (as measured by the Score for Neonatal Acute Physiology [SNAP]) a nd bacteremia both before and after birth weight adjustment. In additi on, the effect of bacteremia on hospital resource use was estimated. R esults. Coagulase-negative staphylococcus was the most common pathogen noted in blood cultures drawn at 48 hours after admission or later. I t was isolated on at least one occasion in 53 patients (cumulative inc idence of 17.5 first episodes per 100 patients). These episodes occurr ed during 7652 days at risk, giving an incidence density of 6.9 initia l bacteremias per 1000 patient-days at risk As expected, when compared with the nonbacteremic group, bacteremic patients were of lower birth weight (888 +/- 231 vs 1127 +/- 258 g; P < .01) and gestational age ( 26.4 +/- 2.1 vs 28.9 +/- 2.8 weeks; P < .01), In addition, these patie nts were more severely ill on admission (SNAP 17.3 +/- 6.5 vs 12.2 +/- 5.8; P < .01). Even after birth weight stratification, the risk of ba cteremia by both measures increased with higher SNAP scores. For examp le, among infants with birth weights greater than 1 kg, 25% of the mos t severely ill patients (SNAP 20 and higher) experienced at least one bacteremic episode, whereas the rates seen in infants with intermediat e (SNAP 10 to 19) and low illness severity (SNAP 0 to 9) were 8.6% and 3.0%, respectively (chi(2) for trend = 7.25; P < .01). Multivariate l inear regression showed that bacteremia was associated with a prolonga tion of neonatal intensive care unit stay of 14.0 +/- 4.0 days (P < .0 1) and an increase in hospital charges of $25 090 +/- 12 051 (P < .05) , even after adjustment for birth weight and admission-day SNAP. Concl usions. Nosocomial coagulase-negative bacteremia is an important compl ication among very low birth weight infants. Assessment of illness sev erity with SNAP provides information regarding nosocomial infection ri sk beyond that available from birth weight alone.