The change in recent years from antiretroviral monotherapy to combination therapy may have important consequences for the use and cost of service provision. We studied the use and costs of hospital services for HIV-infected children managed at St Mary‚s Hospital, London, between 1 January 1986 and 31 December 1994, before the introduction of combination antiretroviral therapy. At this time approximately a quarter of HIV-infected children, short-term survivors, progressed rapidly to AIDS and death during their first year of life, whereas for the remainder, long-term survivors, disease progression was slower. The annual rate of progression to AIDS and death for the long-term survivors was between 6 and 8% after the first year of life[1-4]. When the data were analysed by the stage of HIV infection, we found that the use and cost of hospital services increased with disease severity, but considerable differences were observed between short- and long-term survivors.
During the study period, 119 HIV-infected children attended St Mary‚s, 44% of all reported HIV-infected children in England. Data were abstracted from case notes for 118 of these children and analysed using SAS[6,7]. Service use was recorded for each child at each visit alongside a clinical classification based on the Centers for Disease Control categories of indeterminate, asymptomatic, symptomatic non-AIDS and AIDS  (Table 1).
The mean use of services were calculated per patient-year; one ‚patient-year‚ was defined as 365 days of follow-up at St Mary‚s by stage of HIV infection, and the analytical methods adopted were similar to those used in previous studies[9,10]. The denominator consisted of the total follow-up time for all children by each stage of HIV infection, whereas numerators were calculated by summing the use of each service by all children attending the clinic during the period. Prescribed drugs were summed in the same manner and a ‚drug-day‚ constituted one day on which one drug was prescribed. Prescriptions for multiple drugs for the same patient were added, and therefore the mean number of drug-days per patient-year could exceed 365. For inpatient days and outpatient visits, the χ2 test was used to compare results between short- and long-term survivors, whereas χ2 for trend was used to analyse time trends. Unit cost estimates were obtained from relevant hospital departments through a research-based service-specific costing exercise. Total cost estimates were calculated by linking activity data with relevant units costs. Financial data related to the 1993/94 financial year, indexed to 1995/96 prices.
The mean number of inpatient days per patient year for indeterminate children decreased significantly (χ12trend=120.86, P<0.001), but a significant increase was seen for children with symptomatic non-AIDS (χ12trend=174.13, P<0.001); no significant changes were observed for asymptomatic children or children with AIDS (χ12trend=0.03, P<0.9 and χ12trend=3.6, P<0.06, respectively). The mean number of outpatient visits increased significantly for children with symptomatic non-AIDS (χ12trend=9.96, P=0.002), but no changes were observed for indeterminate, asymptomatic or children with AIDS (χ12trend=2.6, P=0.11; χ12trend=0.01, P=0.75; χ12trend=1.54, P=0.21, respectively). Hospital costs paralleled these changes (Table 1).
Profound differences in the use and cost of hospital services have been observed among adults with AIDS before and during their final 6 months of life[13,14]. In this study, 19 of the 44 children with AIDS died, 11 within 8 months (246 days) of diagnosis with AIDS. The use and cost of hospital services were estimated for the final 6 months of life in the 11 short-term survivors and compared with the final 6 months of life for the long-term survivors. The mean number of inpatient days during the final 6 months on the general ward was 118.3 for short-term survivors compared with 18.3 for long-term survivors (χ12=503.0, P<0.001). The mean number of days spent in paediatric intensive care was 17.3 for short-term survivors compared with 0.3 for long-term survivors (χ12=80.7, P<0.001). The mean number of outpatient visits for short- and long-term survivors were 10.2 and 4.4, respectively (χ12=23.4, P<0.001). The mean number of drug-days for short-term survivors was 1060.3 compared with 1718.2 for long-term survivors, whereas the mean number of tests and procedures performed for short-term survivors was 635.0 compared with 139.1 for long-term survivors. Total hospital costs for the final 6 months of life were higher for short-term survivors, £107888 compared with £24502 for long-term survivors; both figures were higher than average costs per AIDS patient-year (Table 1).
Contrary to trends observed among English adults treated for HIV infection during the same period[9,10], no overall trend from an inpatient- to outpatient-based service was observed among these children. This could be due to policy decisions within the hospital, but evidence of such a shift is now beginning to accumulate, probably related to the increased use of combination antiretroviral therapy[15-17]. However, without access to baseline data such as those provided by this study, the impact of clinical decisions, such as changes in drug therapy, on other aspects of service provision cannot be measured. Future changes in the use, cost and outcome of service provisions for HIV-infected children ought to be monitored through multi-centre prospective information systems[18,19].
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