Burden of non-AIDS-related illness increases as patients with HIV age

Swiss research shows that non-AIDS-related diseases are now a major cause of illness in patients with HIV, and that the risk of such diseases increases with age. The research, which is published in the online edition of Clinical Infectious Diseases, is accompanied by an editorial emphasising the increasing importance of primary care in the management of patients with HIV.

As recently published studies have shown, improvements in treatment and care have increased the life expectancy of many patients with HIV. Nevertheless, these patients still have a higher burden of disease than that observed in the general population, and are likely to develop to the diseases of ageing earlier.

Investigators from the Swiss HIV Cohort Study wished to establish the influence of ageing on the epidemiology of non-HIV-related illnesses in their patients.

They therefore designed a study involving 8444 patients who received care between 2008 and 2010. The incidence and risk of AIDS-related and non-HIV-related illnesses was calculated and compared between patients in three different age groups (under 50, 50 to 64, and above 65).

Overall, the patients had a median age of 45 years. Over two-thirds (68%) were aged under 50, 26% were in the 50 to 64 age group, and 5% were aged 65 or above. Between 1990 and 2010, the proportion of patients aged between 50 and 64 increased from below 3% to over 25%. “If this trend continues over the next decade,” writes the author of the accompanying editorial, “up to 50% of patients in [the Swiss] cohort will be > 50 years of age. Such an outcome was unimaginable 30 years ago, when AIDS was first described.”

Most of the patients (71%) were male, 85% were taking antiretroviral therapy, 81% had an undetectable viral load, and the current median CD4 cell count being 528 cells/mm³. Approximately a third of patients were taking medication for a condition other than HIV.

A total of 2% of patients died. The leading causes of death were cancers, infections, and cardiovascular disease. There were 95 new AIDS defining events, but the total number of non-HIV-related events was a remarkable ten times higher.

The 994 non-AIDS-defining events included 201 cases of bacterial pneumonia, 55 heart attacks, 39 strokes, 70 cases of diabetes, 123 trauma-related fractures, 37 fractures without trauma, and 115 non-AIDS-related cancers.

The mortality rate was 7.81 deaths per 1000 person years, and there were 87.5 hospitalisations per 1000 person years. The incidence of new AIDS-defining events was 4.32 cases per 1000 years, compared to an incidence rate of 53.3 per 1000 person years for any clinical event.

Mortality and hospitalisation rates increased significantly as the patients aged. The mortality rate was 5.92 per 1000 person years for those aged under 50, increasing to 22.5 per 1000 person years for the over 65s (p < 0.001).

Similarly rates of bacterial pneumonia (p = 0.005), stroke (p < 0.001), heart attack (p < 0.001), fracture (p < 0.001), osteoporosis (p < 0.001), diabetes (p < 0.001), and non-AIDS-defining cancer (p < 0.001) all increased significantly as the patients aged.

The association between advancing age and an increased risk of these illnesses remained robust after the investigators adjusted for CD4 cell count, viral load, and duration of HIV infection.

An increasing CD4 cell count reduced the risk of both HIV-related and non-HIV-related illnesses (p < 0.001). A detectable viral load was associated with an increased risk of bacterial pneumonia, HIV-related progression, and some non-HIV-related events (p < 0.001). The risk of AIDS-related and non-HIV-related events was also increased by lifestyle factors, most notably injecting drug use and smoking.

“Non-AIDS comorbidities, particularly cardiovascular disease, osteoporosis, diabetes mellitus, and non-AIDS-defining malignancies become increasingly important in HIV-infected persons and increase with older age,” conclude the investigators. “Because age is a nonmodifiable factor, it is particularly important to carefully screen for and prevent age-related modifiable risks of non-AIDS comorbidity.”

In his accompanying editorial, Dr Michael Saag suggests that the best place for this screening to take place is primary care, noting “primary care providers are very comfortable with management of and, in many ways, are better equipped to manage the myriad of multiple comorbidities that naturally occur in patients as they age.”