Despite the aging of the HIV infected population and the increase in comorbidities9,21,23,25
, hospitalization rates in this US-based cohort have declined in the current HAART era. The current study demonstrates a decrease in inpatient admission rates and inpatient days over a six-year period, 2002 to 2007, with the biggest change in 2005. The notable decrease in 2005 could be due to the availability of ART with once daily dosing and fewer side effects.
Inpatient healthcare utilization has had a generally downward trend since the introduction of HAART. Numerous studies demonstrate a significant decline in hospitalizations in the early HAART era, with a less steep decline in the most recent studies.1–7,10,11
From 1998 to 2002, little or no change in inpatient admission rates was observed in two large multi-state HIV cohorts.9,11
More recent data have documented a decline in hospitalization rates. One study comparing the number of hospital admissions per person living with HIV in 6 states noted a 20% reduction between the years 2000 and 2004.34
Additionally, the HIV Outpatient Study reported a decrease in the hospitalization rate per 100 person-years from 14.93 to 11.21 between the periods 2000–2002 and 2003–2005.1
Our data show a 10% reduction in hospitalization rate between 2002 and 2007; a 25% reduction was demonstrated in the HIV Outpatient Study during a similar time period.1
When evaluating this literature, one must distinguish studies using the hospitalization as the unit of analysis,2,10,34
from studies that use the patient as the unit of analysis. It is possible that the aggregate number of hospitalizations could increase, due to increasing prevalence of HIV infection, but the overall hospitalization rate could nevertheless decline, as in the current study. Future studies will be needed to see if these trends continue as the HIV infected population ages and develops more comorbidities.
Multiple factors could be contributing to this decline in hospitalizations. With the advent of once-daily regimens with fewer side effects and newer antiretroviral agents for resistant HIV, HAART therapy has become easier for providers to administer and for both naïve and experienced patients to tolerate. As a result, there has been a rise in the median CD4 count across time in the HIVRN cohort as well as other groups. Similarly, HIV-1 RNA has decreased from a median of 1,778 copies/mL in 2000 to 400 copies/mL in 2007. Presumably, the introduction of HAART has led to improvement in immune status and a decrease in the proportion of hospitalizations from AIDS defining illnesses (ADI).1,11
After controlling for CD4 and HIV-1 RNA, receipt of HAART did not significantly affect admission rates or total number of inpatient days among the full analytic sample. Although some have theorized that there is an increase in short term morbidity after starting patients on HAART35–37
, in this study, over a longer term, inpatient days per year did not decline for patients on HAART.
In prior studies, mean length of stay per admission steadily declined from nearly 14 days in 1993 to 8.85 days in 2000.2,10
Between 2000 and 2002, mean LOS per admission did not appreciably change in the HIVRN.9
In a multi-state study, mean LOS per admission remained relatively stable, from 8.3 to 8.4 days, between 2000 and 2004.34
Our data demonstrated only slight changes in mean LOS per admission between 2002 and 2007. However, a significant decrease in mean number of inpatient days per year was observed. The decrease in inpatient days reflects the lower admission rates; the length of an individual inpatient episode did not change appreciably.
Disparities in inpatient utilization still exist for women, Blacks, IDUs, and older patients.4,26–28
Multiple studies have demonstrated a higher hospitalization rate for HIV-infected women compared to men.3,9–11,26
Similarly, even after adjustment for other factors, Black race/ethnicity has repeatedly been associated with increased hospitalization rates.9–11,38
It has been hypothesized that patients with lower socioeconomic status have increased hospitalization rates39
; in this study patients with public insurance were more likely to be hospitalized than those with private insurance. These sociodemographic differences were observed despite adjusting for CD4 count, the major indicator of HIV-related health status.
Older age has been associated with increased hospitalization rates in prior research.9
HIV patients older than 50 years of age account for a rising proportion of all inpatient admissions, most likely attributable to comorbidities associated with increasing age, namely diabetes, malignancy, and cardiovascular disease.10,11
Additional studies will need to examine trends in hospitalization diagnoses by age group. Consistent with prior studies, IDUs have higher hospitalization rates than non-IDUs.4,9,27,28
Our data did not differentiate between active and past drug use. Therefore, future studies will be needed to investigate hospitalizations rates comparing active to past drug users.
When compared to the general population, HIV-infected patients have longer than average LOS.40
As immune function improves, HIV patients may be admitted for medical reasons unrelated to HIV diagnosis. Schneider and colleagues noted that HIV-infected patients hospitalized without an opportunistic infection (OI) had shorter length of stay when compared to patients with OIs.41
In addition, data from an international multi-site study conducted during the HAART era examining LOS for treatment of community acquired pneumonia found no significant difference in LOS between HIV-infected and HIV-negative patients.42
These studies indicate that non-HIV-associated conditions can influence LOS, and may ultimately decrease overall HIV LOS and bring it closer to that of the general population.
This study is subject to several limitations. First, sites in our sample were not selected by a statistically derived algorithm and are not nationally representative. However, the sites in the sample do encompass a broad geographic distribution, and multi-site studies afford greater generalizability than single-site studies. Second, HIVRN sites are highly experienced in the treatment of HIV, with high rates of HAART usage and OI prophylaxis.43
Our results may not generalize to sites with less provider experience with HIV, smaller caseload of HIV patients, or rural location. Third, our analysis did not include hospital admission diagnoses. This limited our ability to analyze the relationship between admitting diagnosis and inpatient utilization patterns. Lastly, inpatient utilization may be underestimated if patients were treated at hospitals outside HIVRN sites. Each HIVRN site attempts to capture all utilization data, including care provided at the home institution and by other neighboring providers. An unpublished analysis of Medicaid claims data at one site noted that 96% of all admissions occurred at the home hospital. While this one site demonstrates high retention of care among patients, we are do not have comparable data from other HIVRN sites and cannot be certain that they have similar retention patterns.
In conclusion, annual inpatient hospitalization rates and number of inpatient days per year significantly decreased for HIV patients in this multi-state cohort between 2002 and 2007, with the largest decrease occurring in 2005. Decreased admission rates and inpatient days were associated with high CD4 counts, and low HIV-1 RNA. Women, Blacks, HIV transmission from IDU, and older patients still display relatively high inpatient utilization, pointing to persistence of disparities despite advances in HIV treatment.