Continuous Subcutaneous Insulin Infusion versus Multiple Daily Injections of Insulin

Abstract

Recent meta-analyses in the published medical literature have found improved glycaemic control with continuous subcutaneous insulin infusion (CSII) compared with multiple daily injections (MDI) of insulin for patients with diabetes mellitus. In Australia, CSII is predominantly used in type 1 diabetes mellitus (T1DM) patient populations. OBJECTIVE/INTERVENTION: To project long-term costs and outcomes of CSII (Novorapid or Humalog) compared with MDI (NPH insulin plus Novorapid or Humalog) in adult and adolescent T1DM patients in Australia. The study was a modelling analysis utilising a lifetime horizon in adult and adolescent specialty care T1DM patient populations from Australia. Published Australian diabetes complication costs (adjusted to Australian dollars [$A], year 2006 values), treatment costs and discount rates of 5.0% per annum were applied to costs and clinical outcomes. A lifetime horizon was taken, considering only direct medical costs and excluding indirect and non-medical costs. The validated CORE diabetes model employs standard Markov/Monte Carlo simulation techniques. It was used to simulate diabetes progression in Australian adult (mean age 43 years, duration of diabetes 17 years, mean glycosylated haemoglobin [HbA(1c)] 8.2%) and adolescent (mean age 17 years, duration of diabetes 6 years, mean HbA(1c) 8.9%) patients with baseline characteristics taken predominantly from Australian National Diabetes Information Audit and Benchmarking (ANDIAB) in Australia. The main outcome measures were incremental costs and effectiveness of CSII compared with MDI in Australian adult and adolescent patients with T1DM. Mean direct lifetime costs were $A34,642 higher with CSII treatment than with MDI for adult patients and $A41,779 higher for adolescent patients. Treatment with CSII was associated with an improvement in life expectancy of 0.393 years for adults compared with MDI and 0.537 years for adolescents. The corresponding gains in QALYs were 0.467 QALYs and 0.560 QALYs for adults and adolescents, respectively. This produced incremental cost effectiveness ratios (ICERs) of $A88,220 and $A77,851 per life-year gained for CSII compared with MDI for adult and adolescent T1DM patients, respectively, in Australia. These data also produced corresponding ICERs of $A74,147 per QALY and $A74,661/QALY for adult and adolescent T1DM patients, respectively. Sensitivity analyses suggested that our base-case assumptions were mostly robust with improvements in ICERs for reduction in hypoglycaemic events with CSII treatment and worse ICERs for lower HbA(1c) changes associated with CSII treatment compared with MDI. Our analysis suggests that CSII is associated with ICERs in the range of $A53,022-259,646 per QALY gained, with most ICERs representing good value for money in Australia under the majority of scenarios explored.