Patient Preferences for Noninsulin Diabetes Medications
We performed a systematic review of published studies that describe patient preferences for noninsulin diabetes medications (oral or injectable) in adults with type 2 diabetes. We also examined factors that could influence the risk of bias of study findings. A written study protocol was prepared in accordance with the PRISMA statement, and the review was registered with PROSPERO (systematic review record CRD42012002285).
We searched the PubMed, Embase, CINAHL, and EconLit databases for studies published on or before 23 January 2013. Methodology and content experts within our team developed comprehensive search strategies to identify relevant studies. Our search terms consisted of key words for diabetes medication treatment, as well as methods used to assess patient preferences (e.g., conjoint analysis, decision analysis, utilities, and stated preferences) about medication treatment. The detailed search strategies are included within Supplementary Table 1.
Two reviewers screened all titles independently. Titles were excluded if both reviewers determined that they did not meet inclusion criteria. Remaining articles and those with no titles proceeded to abstract review. Both reviewers independently screened abstracts of all remaining articles. Articles were excluded at this stage if both reviewers determined that they did not meet inclusion criteria. Disagreements about inclusion or exclusion based on abstract review were determined by consensus. Two investigators then reviewed the full text of all remaining articles and those with no abstracts. We included studies if they 1) included adult patients with type 2 diabetes and 2) assessed patient preferences related to medication treatment of type 2 diabetes. We defined a preference as a patient's a priori selection or rating of one treatment alternative over another, given a choice of at least two treatment options. We excluded articles if they 1) were not written in English, 2) did not assess patient treatment preferences, 3) included only patients <18 years old, 4) contained no original data (e.g., review, commentary, editorial, or meeting abstract), 5) only assessed preferences for treating diabetes complications or comorbid medical conditions, 6) only included nonmedication diabetes treatment, 7) only assessed patient satisfaction with or adherence to treatment, or 8) only included insulin therapy. Consensus on study inclusion was reached by at least two reviewers.
For each article that met our inclusion criteria, two reviewers extracted data, including information on study design, treatments compared, locations, sample size, participant characteristics, preference elicitation methods, funding sources, and treatment-related attributes associated with patient preferences. Reviewers resolved disagreements by discussion and adjudication with a third party (i.e., a health economist with expertise in assessing patient treatment preferences).
Two reviewers used a checklist adapted from previously published instruments evaluating general study quality and the Purpose, Respondents, Explanation, Findings, Significance (PREFS) checklist specifically developed based on guidelines for conjoint analysis, PROs, and randomized and nonrandomized trials to independently assess study reporting on factors that could influence the validity of findings, including study external validity (i.e., well-described inclusion and exclusion criteria) and factors influencing study internal validity (i.e., a well-defined study question that includes key PICOTS [population, intervention, comparator, outcomes, timing, and settings] components, a comprehensive description of treatment alternatives, appropriate measurement of patient preferences, appropriate analytical techniques for the given data, and prespecified analysis [Supplementary Table 2]).
We decided a priori not to statistically combine results in a meta-analysis because we expected studies to be methodologically and clinically diverse. For instance, some studies ranked patient preferences using conjoint analysis or an alternative discrete choice experiment whereas others reported patient utilities for a particular treatment. Therefore, we qualitatively synthesized results for individual studies within summary evidence tables to help clarify the similarities and differences among studies that appear to address similar research questions across a variety of measures and patient populations.
Research Design and Methods
Study Design
We performed a systematic review of published studies that describe patient preferences for noninsulin diabetes medications (oral or injectable) in adults with type 2 diabetes. We also examined factors that could influence the risk of bias of study findings. A written study protocol was prepared in accordance with the PRISMA statement, and the review was registered with PROSPERO (systematic review record CRD42012002285).
Data Sources and Searches
We searched the PubMed, Embase, CINAHL, and EconLit databases for studies published on or before 23 January 2013. Methodology and content experts within our team developed comprehensive search strategies to identify relevant studies. Our search terms consisted of key words for diabetes medication treatment, as well as methods used to assess patient preferences (e.g., conjoint analysis, decision analysis, utilities, and stated preferences) about medication treatment. The detailed search strategies are included within Supplementary Table 1.
Study Selection
Two reviewers screened all titles independently. Titles were excluded if both reviewers determined that they did not meet inclusion criteria. Remaining articles and those with no titles proceeded to abstract review. Both reviewers independently screened abstracts of all remaining articles. Articles were excluded at this stage if both reviewers determined that they did not meet inclusion criteria. Disagreements about inclusion or exclusion based on abstract review were determined by consensus. Two investigators then reviewed the full text of all remaining articles and those with no abstracts. We included studies if they 1) included adult patients with type 2 diabetes and 2) assessed patient preferences related to medication treatment of type 2 diabetes. We defined a preference as a patient's a priori selection or rating of one treatment alternative over another, given a choice of at least two treatment options. We excluded articles if they 1) were not written in English, 2) did not assess patient treatment preferences, 3) included only patients <18 years old, 4) contained no original data (e.g., review, commentary, editorial, or meeting abstract), 5) only assessed preferences for treating diabetes complications or comorbid medical conditions, 6) only included nonmedication diabetes treatment, 7) only assessed patient satisfaction with or adherence to treatment, or 8) only included insulin therapy. Consensus on study inclusion was reached by at least two reviewers.
Data Extraction and Quality Assessment
For each article that met our inclusion criteria, two reviewers extracted data, including information on study design, treatments compared, locations, sample size, participant characteristics, preference elicitation methods, funding sources, and treatment-related attributes associated with patient preferences. Reviewers resolved disagreements by discussion and adjudication with a third party (i.e., a health economist with expertise in assessing patient treatment preferences).
Two reviewers used a checklist adapted from previously published instruments evaluating general study quality and the Purpose, Respondents, Explanation, Findings, Significance (PREFS) checklist specifically developed based on guidelines for conjoint analysis, PROs, and randomized and nonrandomized trials to independently assess study reporting on factors that could influence the validity of findings, including study external validity (i.e., well-described inclusion and exclusion criteria) and factors influencing study internal validity (i.e., a well-defined study question that includes key PICOTS [population, intervention, comparator, outcomes, timing, and settings] components, a comprehensive description of treatment alternatives, appropriate measurement of patient preferences, appropriate analytical techniques for the given data, and prespecified analysis [Supplementary Table 2]).
Data Synthesis and Analysis
We decided a priori not to statistically combine results in a meta-analysis because we expected studies to be methodologically and clinically diverse. For instance, some studies ranked patient preferences using conjoint analysis or an alternative discrete choice experiment whereas others reported patient utilities for a particular treatment. Therefore, we qualitatively synthesized results for individual studies within summary evidence tables to help clarify the similarities and differences among studies that appear to address similar research questions across a variety of measures and patient populations.
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