Objective: Stakeholders in the US and elsewhere are interested in country-specific and cohort-specific information with which to assess the long-term value of self-monitoring of blood glucose (SMBG) for patients with type 2 diabetes mellitus (T2DM) on oral anti-diabetes drugs (OADs). This study modeled the cost-effectiveness of SMBG at frequencies of once, twice, or three times per day for this population, and included those who had used SMBG in the prior year.
Research design and methods: Based on clinical findings of a longitudinal Kaiser Permanente study, a validated model was used to project 40-year clinical and economic outcomes for SMBG at (averages of) once, twice, or three times per day versus no SMBG. Baseline HbA1c (7.6%), age and gender represented the Kaiser study 'prevalent' SMBG users cohort. Unit costs came primarily from a 2003 published article; inflated to US$2006. Outcomes were discounted at 3% per annum, with sensitivity analyses on discount rates and time horizons. Analyses were conducted from a third-party payer perspective in the US, including only direct costs.
Main outcome measures: Primary outcomes were differences in total costs, cumulative incidence of complications, quality-adjusted life years (QALYs); and incremental cost-effectiveness ratios (ICERs).
Results: For patients using SMBG once, twice, or three times per day, relative risks over 40 years were lower for 14 of 16 complications and slightly higher for 2 complications. Compared to 'no SMBG,' QALYs increased with SMBG frequency: 0.047, 0.116, and 0.132 QALYs for SMBG once, twice, and three times per day, respectively. Some increased costs with SMBG were offset by reductions in costs for several diabetes-related complications. Corresponding ICERs were $26,206, $18,572 and $25,436/QALY gained. Results were most sensitive to time horizon, with SMBG not cost-effective over a 5-year simulation period.
Conclusions: Study limitations include the use of relatively short-term observational data, unknown levels of patient adherence, and assumptions regarding the duration of clinical effects. Results showed that compared to no SMBG, base case ICERs for each of the three SMBG frequencies examined were below $30,000, and that a portion of the increased costs associated with SMBG were offset by reductions in complication costs, and by modest increases in QALYs. Results add to the literature addressing the cost-effectiveness of SMBG as a component of care for T2DM patients on OADs, and in particular those with monitoring experience within the previous year.