July 13, 2002
One such study in Indianapolis, WePeB5856, attempted to predict adherence rates among 85 patients (50 men, 35 women) at an Indiana clinic using mainly self-reported data. Men were found to make more clinic visits, but medication adherence was approximately the same for both genders. However, more women than men (43 percent vs. 23 percent) were clinically depressed, a condition associated with lower adherence rates. No surprises here: Women overall more frequently suffer from depression than men and depressed people are less likely to take care of other health problems.
By contrast, a nutritional chemoprevention trial in Miami among 234 HIV-positive drug users (51 percent men, 49 percent women) (WePeB5825) reported that men were twice as likely to drop out of the study, independent of their age. Older women were more likely to continue the study, even when they lived in shelters, while men of all ages who lived in shelters or were homeless were three times as likely to drop out than men living at home. These results are also common sense: No fixed housing leads to problems in keeping appointments -- where would you hang your calendar?
Another study attempted to predict only medication adherence (WePeB5823). Rather than relying on self-reporting, however, this study of 130 men and 32 women used medication events monitoring system (MEMS) caps. No difference in adherence based on gender was reported, although the authors noted that cognitive issues (e.g., self-efficacy, intent) were better predictors of adherence in men, while practical issues were more likely to impede adherence in women. Not surprising, either. Many women tend to have more practical issues to begin with (including childrearing responsibilities), which need to be resolved before cognitive issues come into play.
Some studies explored medical differences in male and female responses to treatment and the differing side effects of such treatment.
Patients enrolled in a trial for an investigational HIV drug (capravirine) were assessed for hyperamylasemia (MoPeC3516). Of the 615 patients studied, 23 percent had the condition. Women were more likely to suffer from hyperamylasemia than men were. Authors noted that doctors should be aware of this correlation when diagnosing HIV patients, but gave no explanation for this correlation.
While all studies reviewed so far were conducted in the U.S., data for a presentation on gender differences in HIV progression (WePeC6063) came from a Spanish study. Of the 226 study subjects, 20 percent were women. Women were younger at seroconversion, more likely to be prescribed antiretroviral medication (36.4 percent vs. 31 percent of men) and progressed more slowly towards AIDS and, ultimately, death. Study authors speculated that this could be due to higher pre-AIDS mortality and/or earlier start of medication.
Response to initial highly active antiretroviral treatment of nelfinavir and dual NRTIs, however, was independent of gender in another study conducted in the U.S. (WePeB5967). Better virologic outcome was associated with lack of antiretroviral treatment prior to start of HAART, not gender. So, antiretroviral treatment-naive patients respond better to HAART because they haven't yet developed resistance to certain medications. This trend may change as more people are infected by HIV strains that are already drug-resistant.
CD4+ cell increases in response to HAART, however, seemed to be determined by gender. Women's CD4+ cell counts responded better to sustained virologic suppression from HAART than men's in another U.S. study conducted in Texas (WePeB5965). Surprisingly, treatment regimens with few, or no, protease inhibitors seemed to improve CD4+ count more than treatments that included PIs. Study authors note that treatment recommendations need to be defined separately for men and women. I would go even further: Given the differing average body weights of men and women, different drug dosage sizes may need to be offered, as well.
The Atlantic Study, conducted in Los Angeles and Amsterdam, (TuPeB4455) attempted to determine whether toxicity after HAART differed in men and women. Of the 59 women and 239 men enrolled, men had higher laboratory toxicities, but more severe toxicities were evenly distributed among men and women. The authors noted that very few trials studied gender as a variable in HAART response and those that did yielded conflicting results. They therefore recommend that gender be included as a standard variable in future trials.
One study from Spain actually focused on gender bias in clinical trials (WePeB5964). In 49 trials conducted between 1990 and 2000, researchers noted that none provided analysis by sex. Only two specified a stratified analysis by sex and only one trial investigated gender differences in its discussion section. The authors conclude that trial design itself prevents researchers from obtaining gender-related information.
Two presentations examined gender-related differences in cause of death for HIV-infected adults and children. The adult study (MoPeC337) investigated the deaths of 772 of the 4180 persons seen at a Chicago clinic. No differences between men and women in non-HIV related causes of death were reported overall. Although at the start of HAART use, more women than men died from non-HIV related causes. So were there gender differences in HIV-related causes of death? The poster doesn't say.
In the study of perinatally-infected HIV-positive children in New York City (MoPeC3346), survival rates and AIDS incidence were similar for boys and girls. However, boys were more likely to develop lymphocytic interstitial pneumonitis, while girls tended to develop esophageal candidasis more often than boys. Since physical differences (including average size, muscle development, etc.) between the genders are less pronounced in childhood, one would expect that boys and girls respond similarly to the same treatment.
Hospitalization rates for HIV-infected adult patients were studied at a Miami hospital (WePeB5973). Among the 84 men and 57 women in the study, women were eight times more likely than men to have been admitted to the hospital multiple times and three times as likely as men to log more than ten hospital admissions. The authors did not offer an explanation for this difference, but suggested further study of this issue. The question, however, may not be why women were hospitalized more frequently, but why men weren't. Some men may not have sought -- or received -- medical care when they should have been hospitalized, resulting in lower hospitalization rates for them.
All in all, nothing much new or surprising. I would, however, have expected medical trial designers to pay more attention to gender as a variable than they appear to have done. This is, after all, not the 19th century, when women were seen as simply an (subordinate) extension of men.
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