Effect of lifestyle modification on risk factors for cardiovascular disease and metabolic syndrome
9 October 2006. Related: Conference reports, Side effects, Lipodystrophy and metabolic complications, Lipodystrophy Workshop (IWADRW) 8th San Francisco 2006.
Simon Collins, HIV i-Base
Steven Grinspoon from Massachusetts General Hospital presented results from a study of lifestyle modifications on metabolic syndrome criteria and cardiovascular parameters in HIV-positive patients with the metabolic syndrome. [1]
Previous studies have indicated that 17-45% HIV-positive patients have metabolic syndrome and that the relative risk for developing cardiovascular disease of type-2 diabetes mellitus (T2DM) are also higher in HIV-positive compared to HIV-negative men diagnosed with metabolic syndrome.
The study randomised 34 patients to an intensive 6-month lifestyle modification intervention, modeled on the Diabetes Prevention Programme, or to standard health advice. The intervention included 1-2-1 weekly counseling with a dietician, as part of a diet and exercise programme.
The dietary aims included reducing daily calories intake from fat to <35%, with <7% calories from saturated fat and at least 25-35 grams of soluble or insoluble fibre. Up to 10% and 20% calories could come from polyunsaturated and monusaturated fats respectively. The exercise component included 3 hours of physical activity each week, and 10,000 steps daily measured with a podometer.
Baseline characteristics of the study group included mean age of 45 (+/-2), 50% were smokers (39% in the control group), 50% were African-American, and over 60% were women, and are detailed in Table 1. Over 90% of patients were using RTIs, 50% were using PIs and 44% were using NNRTIs in their ARV regimen. While half the patients were using blood pressure medication, only 5-11% were using lipid lowering drugs (LLD). Waist circumference was the only statistically significant difference between the two groups at baseline.
Table 1: Baseline characteristics
| Intervention | Control | p-value | |
|---|---|---|---|
| Age | 45 ±2 | 46 ±2 | NS |
| African American | 69% | 56% | NS |
| Male/female | 37/63% | 33/67% | NS |
| Smoker | 50% | 39% | NS |
| Duration HIV | 128 mo | 124 mo | nS |
| Current blood pressure Rx | 56% | 50% | NS |
| Lipids Rx | 6% | 11% | NS |
| Waist (cms) | 113 | 101 | 0.001 |
| TG (mg/dL) | 176 ±23 | 263 ±50 | NS |
| HDL (mg/dL) | 48 ±3 | 41 ±2 | NS |
NS: non significant
Six patients discontinued the study early: 4 in the intervention arm (2 LTFU, 1 pregnancy, 1 family death) and 2 in the control arm (1 LTFU, 1 anemia).
Table 2: Results at 6 months
| Intervention | Standard advice | p-value | |
|---|---|---|---|
| Waist circumference (cms) | -2.6 ±1.1 | 1.2 ±1 | 0.022 |
| Blood pressure (mmHg) | -13 ±4 | 4 ±4 | 0.008 |
| Triglycerides | -1 ±22 | -25 ±34 | 0.550 |
| HDL cholesterol | 3 ±22 | 0 ±2 | 0.396 |
| Fasting glucose mmol/L | 0.17 ±0.17 | 0.06 ±0.11 | 0.716 |
| Systolic BP | -13 ±-4 | 4 ±-4 | 0.008 |
| Diastolic BP | -2 ±-3 | 1 ±-3 | 0.498 |
| HgbA1C | -0.1% | +0.25 | 0.017 |
In the intervention arm, caloric intake reduced by approximately -350 kcal/day (p=0.068), with the percentage of calories from saturated fatty acids dropping by 2% (p=0.040) and fibre intake increasing by 4g/day (p=0.057), with no changes in the control group. Exercise increased by approximately +16 hours/week (p=0.014 compared to control). At month 6, significant improvements in some parameters included in the metabolic syndrome were reported in the intervention group and are detailed in Table 2.
COMMENT
Although this was a small study and lipid markers (TC, LDL and HDL) were not helped, lifestyle modification significantly improved some of the markers associated with metabolic syndrome. The study only had short-term follow-up for some benefits that would be expected to accumulate further over time if the programme was maintained.
For example, previous research with the Dietary Prevention Programme intervention with 3 year follow-up showed that lifestyle changes reduced cumulative incidence of diabetes by 58% compared to control patients. In this placebo controlled randomised study in older patients with impaired glucose tolerance, the reduction in risk from use of metformin was only 31%. [2]
Given current ARV choices, supporting lifestyle changes is currently one of the most optimistic interventions to reduce risk of CVD and T2DM in high-risk patients. It is disappointing that so few studies have focused on this area, as similar to smoking cessation programmes, these are also likely to have long-term cost benefit advantages.
References:
- Fitch KV, Anderson EG, Grinspoon S et al. Effects of a lifestyle modification programme inHIV-infected patients with the metabolic syndrome. 8th IWADRLH, September 2006, San Francisco. Abstract 24.
- Knowler WC, Barrett-Connor E, Fowler SE et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. NEJM 2002 Feb 7;346(6):393-403. PubMed ID: 11832527.