The average life-years gained using the lifestyle intervention over the standard care in overweight, borderline and moderately obese patients were 0.01 years for both men and women.
The average QALYs gained using the lifestyle intervention over standard care were 0.23 in overweight women and 0.25 in overweight men, 0.25 in borderline women and 0.28 in borderline men, and 0.26 in moderately obese women and 0.29 in moderately obese men.
The average incremental costs of the lifestyle intervention over standard care were CHF 510 in overweight women and CHF 490 in overweight men, CHF 80 in borderline women and CHF -6 in borderline men, and CHF 207 in moderately obese women and CHF 127 in moderately obese men.
The costs and benefits were combined using an incremental cost-effectiveness ratio (ICER, the additional cost per life-year gained when the lifestyle intervention was compared with standard care), and using an incremental cost-utility ratio (ICUR, the additional cost per QALY gained when the lifestyle intervention was compared with standard care).
For overweight patients, the ICER ranged from CHF 17,149 for 55-year-old men to CHF 295,863 in 25-year-old women, whereas the ICUR ranged from CHF 914 for 55-year-old men to CHF 6,286 for 25-year-old women.
For borderline patients, the lifestyle intervention was found to be dominant (more effective and less costly). The ICER ranged from dominant in all male age groups to CHF 242,619 for 25-year-old women and the ICUR ranged from dominant in all male age groups to CHF 3,023 in 25-year-old women.
For obese patients, the ICER ranged from dominant for 45- and 55-year-old men to CHF 171,544 for 25-year-old women, whilst the ICUR ranged from dominant for 55-year-old men and 35-year-old women to CHF 3,180 for 25-year-old women.
The results of the probabilistic sensitivity analyses showed that, when the cost-effectiveness threshold was CHF 0, the probability of the lifestyle intervention being cost-effective was 5% in the overweight group, 78% in the borderline group, and 47% in the moderately obese group. If the cost-effectiveness threshold rose to CHF 1,000, the probability of the lifestyle intervention being cost-effective increased to 35% in overweight patients, 99% in borderline patients, and 92% in moderately obese patients.