An ultrasound measurement of fat thickness around the kidneys can accurately predict which HAART-naïve individuals will develop both the body shape disturbances and metabolic abnormalities associated with lipodystrophy syndrome, according to Spanish research published in the July 15th edition of Clinical Infectious Diseases, which is now available on-line. The investigators also found that the procedure could also accurately determine which individuals switching anti-HIV drugs because of body shape changes were most likely to see an improvement in their condition.
A total of 74 HIV-positive individuals were recruited to the study between 2000 and 2003. At baseline, 22 of these individuals were naïve to HAART. The investigators wished to see which of a series of blood tests, body measurements, and scans could most accurately predict the development of lipodystrophy.
Blood samples were taken at baseline and every three months to monitor CD4 cell count, HIV viral load, total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, liver and kidney function, lactate levels, and insulin and glucose levels.
Both individuals and doctors conducted visual assessments to determine the existence of body shape changes. Skin-fold thickness was also measured at the shoulder, triceps, abdomen and thigh, and waist-to-hip ratio was monitored.
In addition, investigators used ultrasound to assesses the thickness of subcutaneous fat and the thickness of fat around the kidneys (perirenal fat diameter, PRFD).
As expected, blood lipids were significantly higher in HAART-treated patients than in the 22 individuals who were naïve to HIV therapy. What’s more, the investigators found that amongst the HAART-naïve group, total cholesterol, LDL cholesterol and triglycerides were higher in those individuals who went on to develop lipodystrophy than those who did not. This difference reached statistical significance nine months after starting HAART.
The investigators also found that skin-fold thickness and hip-to-thigh ratio differed between the treatment-naïve and treatment experienced patients. This was expected.
At baseline, perirenal fat diameter was considerably lower in HAART-naïve patients. The treatment-naïve individuals who developed lipodystrophy during follow-up experienced a progressive increase in the thickness of fat around their kidneys. This was not seen in the patients who were naïve at baseline and did not develop lipodystrophy.
A perirenal fat diameter of greater than 2.6mm at baseline in treatment-naïve individuals was predictive of the development of metabolic or body fat changes during follow-up. In patients already taking treatment, a perirenal fat diameter of 4.6mm or greater was associated with a diagnosis of lipodystrophy.
In all 72 patients, increasing perirenal fat diameter correlated with increasing levels of total cholesterol (p = 0.001), triglycerides (p = 0.12), and LDL cholesterol (p = 0.001). Increasing perirenal fat diameter was also associated with increased glucose (p = 0.02), and insulin (p = 0.003).
Amongst the HAART-naïve patients, those with a perirenal fat diameter of above 2.6mm experienced significant loss of subcutaneous fat in both the arms (p = 0.043), and legs (p = 0.004) during follow-up. No significant changes in the thickness of subcutaneous fat in the arms or legs was seen during follow-up in the treatment-naïve individuals with a perirenal fat diameter less than 2.6mm.
The investigators also found that perirenal fat diameter was lower in the four treatment-experienced patients who experienced an improvement in their lipodystrophy after switching their HAART regimen (p
Amongst the treatment-naïve patients who developed lipodystrophy during follow-up the first parameter included in the investigators analysis to predict either a change in body shape or metabolic abnormalities was perirenal fat diameter (p = 0.001).
The investigators acknowledge that their study involved a small number of patients. However they believe that their data “suggest that detection of an increase in PRFD by ecnography could be a reliable parameter to predict lipodystrophy.” They add, “our findings suggest that echographic detection of a PRFD >2.6 or >4.9 at baseline or during follow-up, retrospectively, is suggestive of a predisposition to develop lipodystrophy.” Another benefit of this diagnostic tool appeared to be its ability to predict which patients switching treatment would experience an improvement in their lipodystrophy.
The investigators conclude that measuring perirenal fat diameter is cheap, simple, and safe, and “its…advantages make it the first-choice procedure for the evaluation of this complication.”
Further information on this website
Lipodystrophy - booklet in the information for HIV-positive people series (pdf)
Asensi V et al. Perirenal fat diameter measured by echography could be an early predictor of lipodystrophy in HIV type 1-infected patients receiving highly active antiretroviral therapy. Clinical Infectious Diseases 39 (on-line edition), 2004.