Abstract
BACKGROUND: Type 2 diabetes is a significant public health concern. With the completion of the Diabetes Prevention Program, there has been a proliferation of studies attempting to translate this evidence base into practice. However, the cost, effectiveness, and cost-effectiveness of these adapted interventions is unknown. OBJECTIVE: The purpose of this systematic review was to conduct a comprehensive meta-analysis to synthesize the effectiveness, cost, and cost-effectiveness of lifestyle diabetes prevention interventions and compare effects by intervention delivery agent (dietitian vs non-dietitian) and channel (in-person vs technology-delivered). METHODS: English and full-text research articles published up to July 2015 were identified using the Cochrane Library, PubMed, Education Resources Information Center, CAB Direct, Science Direct, and Google Scholar. Sixty-nine studies met inclusion criteria. Most employed both dietary and physical activity intervention components (four of 69 were diet-only interventions). Changes in weight, fasting and 2-hour blood glucose concentration, and hemoglobin A1c were extracted from each article. Heterogeneity was measured by the I(2) index, and study-specific effect sizes or mean differences were pooled using a random effects model when heterogeneity was confirmed. RESULTS: Participants receiving intervention with nutrition education experienced a reduction of 2.07 kg (95% CI 1.52 to 2.62; P<0.001; I(2)=90.99%, 95% CI 88.61% to 92.87%) in weight at 12 months with effect sizes over time ranging from small (0.17, 95% CI 0.04 to 0.30; P=0.012; I(2)= 86.83%, 95% CI 80.42% to 91.14%) to medium (0.65, 95% CI 0.49 to 0.82; P<0.001; I(2)=98.75%, 95% CI 98.52% to 98.94). Effect sizes for 2-hour blood glucose and hemoglobin A1c level changes ranged from small to medium. The meta-regression analysis revealed a larger relative weight loss in dietitian-delivered interventions than in those delivered by nondietitians (full sample: -1.0 kg; US subsample: -2.4 kg), and did not find statistical evidence that the delivery channel was an important predictor of weight loss. The average cost per kilogram weight loss ranged from $34.06 over 6 months to $1,005.36 over 12 months. The cost of intervention per participant delivered by dietitians was lower than interventions delivered by non-dietitians, although few studies reported costs. CONCLUSIONS: Lifestyle interventions are effective in reducing body weight and glucose-related outcomes. Dietitian-delivered interventions, compared with those delivered by other personnel, achieved greater weight reduction. No consistent trend was identified across different delivery channels.