Measuring waist circumference and triglyceride levels may be
an easy way of identifying which HIV-positive patients have an increased risk
of cardiovascular disease, according to research published in PLoS One.
Italian investigators found a consistent and significant
relationship between the two measures and the risk factors of cardiovascular disease
in HIV-positive men and women.
Some older HIV therapies were associated with changes in
body fat composition known as lipodystrophy. The syndrome includes the
accumulation of visceral adipose fat and/or fat wasting for the face, limbs,
and buttocks. The investigators note that these body fat changes have been
associated with “the classic constellation of cardiovascular risk factors.”
Indeed, cardiovascular disease is an increasingly important cause of serious
illness and death in patients with HIV.
However, only a minority of HIV-positive patients develop
lipodystrophy and its associated cardiovascular complications. “Therefore,”
suggest the investigators, “there exists an unmet need for a simple yet
accurate clinical tool to discern the high-risk from the low-risk HIV-infected patient.”
A combination of elevated waist circumference and
triglycerides – known as the hypertriglyceridemic waist phenotype – has been
used for over a decade to identify HIV-negative patients with an increased risk
of cardiovascular disease.
The investigators therefore designed a cross sectional study
involing 2322 patients, 841 of whom were women, who received care at an HIV
metabolic clinic between 2005 and 2009.
Triglyceride levels were monitored using blood tests and the
patients’ waist circumference was measured. In addition, DEXA scans were used
to assess the patients’ regional fat and fat free mass, and visceral adipose
tissue and abdominal subcutaneous fat was measured using CT scanning. .
Waist circumference was classified as high if it was above
90 cm in men and 85 cm in women. The cut off point for high triglycerides was
2.0 mmol/l for men and 1.5 mmol/l for women.
The patients were placed into once of four categories:
- Low waist circumference/low triglycerides.
- Low waist circumference/high triglycerides.
- High waist circumference/low triglycerides.
- High waist circumference/high triglycerides.
Investigators then explored the relationship between waist
circumference and triglycerides and a number of factors associated with an
increased risk of cardiovascular disease, such as Framingham risk score,
hypertension, metabolic syndrome, and type-2 diabetes.
Overall, 27% of men and 20% of women had a high waist
circumference accompanied by high triglycerides, and these patients were
significantly older and less physically active (p < 0.05) than patients in
the other groups.
After controlling for these differences in age and exercise
levels, the investigators found a consistent relationship between high waist
circumference/high triglycerides and cardiovascular risk factors in men.
For example, the prevalence of metabolic syndrome was
significantly higher among men in the high waist circumference/high
triglycerides than all other groups (48% vs 4-32%; p < 0.05). Similarly,
prevalence of type-2 diabetes was elevated (16% vs 6-7%; p < 0.05), and men
with high waist circumference/high triglycerides also had a higher Framingham
risk score than men in the other three groups (10 vs 5.8-9.5; p < 0.05).
Prevalence of cardiovascular risk factors was significantly
higher for women in the high waist circumference/high triglycerides group.
Women in this category were more likely to have metabolic
syndrome (56% vs 2-26%; p < 0.05), diabetes (12% vs 4%; p < 0.05),
hypertension (31% vs 14%; p < 0.05), and also a higher Framingham score
(2.9 vs 1.5; p < 0.05) than women in the other categories.
“The combination of waist circumference and triglycerides
was shown to discriminate high-risk and low-risk HIV-infected men and women,”
write the authors, “the present findings suggest a utility of waist
circumference combined with triglyceride levels as a simple clinical tool for
discerning the severity of lipodystrophy and associated cardiovascular risk.”
HIV treatment history and nadir CD4 cell count did not
affect these findings.
There was also a high prevalence of the mixed form of
lipodystrophy (58% and 64%) in both men and women with high waist
The investigators conclude, “these findings suggest that a
waist circumference above 90 cm and triglycerides above 2.0 mmol/l among
HIV-infected men and a waist circumference above 85 cm and triglycerides above
1.5 mmol/l among HIV-infected women discriminates the high from the low-risk
patient in terms of body composition as well as cardiovascular risk.”