HIV associated with an increased risk of cataract surgery

HIV-positive patients are signficantly more likely to undergo surgery to remove cataracts in the eye, according to Danish research published in Clinical Infectious Diseases. A low CD4 cell count before and after the initiation of antiretroviral therapy was associated with cataracts, but there was no evidence that any individual anti-HIV drug was associated with an elevated risk of the condition.

Cataracts are cloudy patches that develop on the lens of the eye, either as a result of ageing or as a long-term consequence of viral infections and inflammation affecting the eye. Long-term corticosteroid treatment may also raise the risk of cataract development.

The investigators suggest that cataracts may be one of the “diseases of ageing” associated with HIV. They add that doctors should be aware of the condition, “however, taking the level of excess risk into consideration, there seems to be no indication for special ophthalmic examinations for cataracts or changes in treatment strategies.”

Advances in treatment and care have resulted in dramatic improvements in the life expectancy of patients with HIV. Nevertheless, the anticipated life span of HIV-positive patients is still shorter than that of the general population. This is partly because patients with HIV have an increased risk of so-called diseases of ageing – for example cardiovascular disease, kidney and liver problems, osteoporosis, and some cancers. The exact reasons for this are controversial, but could include immune suppression, the inflammatory effects of HIV, co-infections, life-style factors, and the side-effects of some antiretroviral drugs.

Cataracts are well recognised as a disease of older age, and Danish investigators wished to see if they occurred with greater frequency in HIV-positive patients than in the general population.

Their study sample included the 5315 patients in the Danish national HIV cohort. Each patient was matched with ten HIV-negative individuals of the same sex and a similar age from the general Danish population.

The investigators compared the incidence of cataract surgery between the HIV-positive and HIV-negative populations. They also conducted a series of analyses to see if there were any factors associated with cataract formation in the HIV-positive patients.

Three-quarters of the HIV-positive patients were men and their median age was 37 years. A total of 44, 561 person years of follow-up were contributed by the HIV-positive individuals, and 555, 902 person years by the control population.

Cataract surgery was performed on 90 (1.7%) HIV-positive patients and 718 (1.4%) of controls. Eye disease that can predispose an individual to cataracts was detected in 252 (5%) of the patients with HIV and 494 (1%) of the HIV-negative individuals.

Overall the investigators found a higher risk of cataract surgery in the HIV-positive population compared to the controls (IRR = 1.87%; 95% CI, 1.50-2.33).

A CD4 cell count below 200 cells/mm³ was associated with an increased risk of cataract surgery, both before starting HIV treatment (IRR = 3.11; 95% CI, 1.26-7.63) and after starting such treatment (IRR = 4.74; 95% CI, 2.60-8.62).

Comparison with the HIV-negative controls showed that HIV-infected individuals treated with antiretroviral drugs and a CD4 cell count above 200 cells/mm³ also had a significantly increased risk of cataract surgery (IRR = 1.87; 95% CI, 1.46-2.39).

Nevertheless there was no evidence that any individual antiretroviral drug increased the risk of cataracts.

“This study found a higher risk of cataract surgery in HIV-infected individuals compared with a non-HIV-infected age- and sex-matched comparison cohort,” comment the investigators. “Although the risk of ocular disease predisposing to cataract is higher in HIV-infected individuals, we found the risk of cataract surgery was not driven only by the high occurrence of such events.”

They emphasise that a CD4 cell count below 200 cells/mm³ appeared to be associated with an especially increased risk of cataracts regardless of the use of HIV therapy, adding “no statistically significant excess risk was observed after initiation of abacavir, tenofovir, PIs [protease inhibitors], or NNRTIs [non-nucleoside reverse transcriptase inhibitors].”

The increased risk was apparent in all age ranges above 35 years of age.

The investigators are uncertain about the exact reasons why infection with HIV is associated with an increased risk of cataracts. Ocular disease was considered as a possible cause, as were the side-effects caused by anti-HIV drugs.

However, they add that the use of HIV therapy “could also be an indicator of a population at increased risk of developing illness rather than indicating the toxic effect on the eye induced by HAART [highly active antiretroviral therapy].”

Mindful that HIV has been associated with an increased risk of cardiovascular disease and other diseases of aging, the investigators conclude, “accelerated aging in the HIV-infected population cannot be excluded as a possible part of the explanation.”

Rasmussen LD et al. Risk of cataract surgery in HIV-infected individuals: a Danish nationwide population-based cohort study. Clin Infect Dis, doi: 10.1093/cid/cir675, 2011 (click here for the free abstract).