The impact of using different imputation methods for missing quality of life scores on the estimation of the cost-effectiveness of lung-volume-reduction surgery.

A post hoc analysis of data from a prospective cost-effectiveness analysis (CEA) conducted alongside a randomized controlled trial (National Emphysema Treatment Trial - NETT) was used to assess the impact of using different imputation methods for missing quality of life data on the estimation of the incremental cost-effectiveness ratio (ICER). The NETT compared lung-volume-reduction surgery plus medical therapy with medical therapy alone in patients with severe chronic obstructive pulmonary disease due to emphysema. One thousand sixty-six patients were followed for up to 3 years after randomization. The cost per quality-adjusted life-year gained was obtained, computing costs from a societal perspective and using the self-administered Quality of Well Being questionnaire to measure quality of life. Different methods of imputation resulted in substantial differences in ICERs as well as differences in estimates of the uncertainty in the point estimates as reflected in the CEA acceptability curves. Paradoxically, the use of a conservative single imputation method resulted in relatively less uncertainty (anticonservative) about the ICER. Owing to the effects of different imputation methods for missing quality of life data on the estimation of the ICER, we recommend use of a minimum of two imputation methods that always include multiple imputation.

[1]  R. Kaplan Decisions about prostate cancer screening in managed care. , 1997, Current opinion in oncology.

[2]  D. Rubin,et al.  Multiple Imputation for Interval Estimation from Simple Random Samples with Ignorable Nonresponse , 1986 .

[3]  Nicholas J. Horton,et al.  Multiple Imputation in Practice , 2001 .

[4]  Steven Piantadosi,et al.  A randomized trial comparing lung-volume-reduction surgery with medical therapy for severe emphysema. , 2003, The New England journal of medicine.

[5]  A L Gould,et al.  A new approach to the analysis of clinical drug trials with withdrawals. , 1980, Biometrics.

[6]  Andrew Briggs,et al.  Missing... presumed at random: cost-analysis of incomplete data. , 2003, Health economics.

[7]  Ruth Etzioni,et al.  Cost effectiveness of lung-volume-reduction surgery for patients with severe emphysema. , 2003, The New England journal of medicine.

[8]  Jan B Oostenbrink,et al.  The analysis of incomplete cost data due to dropout. , 2005, Health economics.

[9]  E. Feuer,et al.  Estimating medical costs from incomplete follow-up data. , 1997, Biometrics.

[10]  Steven Piantadosi,et al.  Patients at high risk of death after lung-volume-reduction surgery. , 2001, The New England journal of medicine.

[11]  D. Rubin Multiple Imputation After 18+ Years , 1996 .

[12]  M. R. Mölken,et al.  Statistical analysis of cost outcomes in a randomized controlled clinical trial. , 1994 .

[13]  N. Zethraeus,et al.  Definition, interpretation and calculation of cost-effectiveness acceptability curves. , 2000, Health economics.

[14]  R. Willke,et al.  Good research practices for cost-effectiveness analysis alongside clinical trials: the ISPOR RCT-CEA Task Force report. , 2005, Value in health : the journal of the International Society for Pharmacoeconomics and Outcomes Research.