Purpose: The purpose of this study was to estimate the (quality-adjusted) life-year gains and lifetime costs of 2-year, 5-year and lifelong lifestyle intervention (diet and exercise) compared to immediate switch to insulin in patients with poorly controlled type 2 diabetes.
Method: We simulated the disease course including complications, quality-adjusted survival, and lifetime costs of the three durations of lifestyle intervention and of immediate switch to insulin using the UKPDS Outcomes Model. A randomized trial provided data on impact of lifestyle changes on risk factors. Unit costs were taken from various local data sources. The costs of intervention, medication, equipment and GP-visits were calculated in a separate spreadsheet. Quality-of-life data were taken from a survey of patients with diabetes in Norway.
Result: The quality-adjusted life-expectancy with immediate switch to insulin and with 2-year, 5-year and lifelong lifestyle intervention was 7.67, 7.71, 7.75, 7.86, respectively, with lifelong discounted costs of $44,318, $80,084, $124,882 and $221,407. The incremental cost per quality-adjusted life-year (QALY) for lifestyle intervention versus immediate switch to insulin were $943,905, $992,210 and $916,104 for 2-year, 5-year and lifelong treatment. The largest cost driver was indirect costs incurred by the patients' participation in diet and exercise sessions and time spent on travel to these sessions. When disregarding indirect costs, the incremental costs per QALY gained for the respective strategies were $6,353, $8,637 and $5,258.
Conclusion: The results from this study indicate that the cost-effectiveness of lifestyle intervention in patients with poorly controlled type 2 diabetes is largely dependant on how time costs are valued. Lifestyle interventions are cost-effective only if indirect costs or the value of time is set to zero or nearly zero.