Is the whole larger than the sum of its parts? Impact of missing data imputation in economic evaluation conducted alongside randomized controlled trials

Handling Missing Data in Health Economics and Outcomes Research (HEOR): A Systematic Review and Practical Recommendations

BACKGROUND

Missing data in costs and/or health outcomes and in confounding variables can create bias in the inference of health economics and outcomes research studies, which in turn can lead to inappropriate policies. Most of the literature focuses on handling missing data in randomized controlled trials, which are not necessarily always the data used in health economics and outcomes research.

OBJECTIVES

We aimed to provide an overview on missing data issues and how to address incomplete data and report the findings of a systematic literature review of methods used to deal with missing data in health economics and outcomes research studies that focused on cost, utility, and patient-reported outcomes.

METHODS

A systematic search of papers published in English language until the end of the year 2020 was carried out in PubMed. Studies using statistical methods to handle missing data for analyses of cost, utility, or patient-reported outcome data were included, as were reviews and guidance papers on handling missing data for those outcomes. The data extraction was conducted with a focus on the context of the study, the type of missing data, and the methods used to tackle missing data.

RESULTS

From 1433 identified records, 40 papers were included. Thirteen studies were economic evaluations. Thirty studies used multiple imputation with 17 studies using multiple imputation by chained equation, while 15 studies used a complete-case analysis. Seventeen studies addressed missing cost data and 23 studies dealt with missing outcome data. Eleven studies reported a single method while 20 studies used multiple methods to address missing data.

CONCLUSIONS

Several health economics and outcomes research studies did not offer a justification of their approach of handling missing data and some used only a single method without a sensitivity analysis. This systematic literature review highlights the importance of considering the missingness mechanism and including sensitivity analyses when planning, analyzing, and reporting health economics and outcomes research studies.

Economic evaluation of pharmacogenomic-guided antiplatelet treatment in Spanish patients suffering from acute coronary syndrome participating in the U-PGx PREPARE study

BACKGROUND

Cardiovascular diseases and especially Acute Coronary Syndrome (ACS) constitute a major health issue impacting millions of patients worldwide. Being a leading cause of death and hospital admissions in many European countries including Spain, it accounts for enormous amounts of healthcare expenditures for its management. Clopidogrel is one of the oldest antiplatelet medications used as standard of care in ACS.

METHODS

In this study, we performed an economic evaluation study to estimate whether a genome-guided clopidogrel treatment is cost-effective compared to conventional one in a large cohort of 243 individuals of Spanish origin suffering from ACS and treated with clopidogrel. Data were derived from the U-PGx PREPARE clinical trial. Effectiveness was measured as survival of individuals while study data on safety and efficacy, as well as on resource utilization associated with each adverse drug reaction were used to measure costs to treat these adverse drug reactions. A generalized linear regression model was used to estimate cost differences for both study groups.

RESULTS

Based on our findings, PGx-guided treatment group is cost-effective. PGx-guided treatment demonstrated to have 50% less hospital admissions, reduced emergency visits and almost 13% less ADRs compared to the non-PGx approach with mean QALY 1.07 (95% CI, 1.04-1.10) versus 1.06 (95% CI, 1.03-1.09) for the control group, while life years for both groups were 1.24 (95% CI, 1.20-1.26) and 1.23 (95% CI, 1.19-1.26), respectively. The mean total cost of PGx-guided treatment was 50% less expensive than conventional therapy with clopidogrel [€883 (95% UI, €316-€1582), compared to €1,755 (95% UI, €765-€2949)].

CONCLUSION

These findings suggest that PGx-guided clopidogrel treatment represents a cost-effective option for patients suffering from ACS in the Spanish healthcare setting.

The Cost-Effectiveness of a Dance and Yoga Intervention for Girls with Functional Abdominal Pain Disorders

BACKGROUND

Functional abdominal pain disorders (FAPDs) affect children worldwide, being more prevalent among girls. The individual and societal burdens of the disease are substantial, and evidence-based interventions are needed. Non-pharmacological treatments have generally produced promising results, with dance and yoga specifically having potential as an effective treatment option. Beside efficacy, the cost-effectiveness of interventions is important when prioritizing and allocating public resources.

OBJECTIVE

This study evaluated the cost-effectiveness of an 8-month dance and yoga intervention for girls with functional abdominal pain or irritable bowel syndrome, based on a randomized control trial called 'Just in TIME'.

METHODS

The intervention, performed in Sweden, was studied using a decision analysis tool, i.e., a decision tree within the trial followed by a Markov model with a time horizon of 10 years. The base case considered healthcare costs as well as productivity losses, measuring the effects in gained quality-adjusted life-years (QALYs) and presenting an incremental cost-effectiveness ratio (ICER).

RESULTS

The base case results show that the intervention, compared with current practice, was the dominant strategy from both the 12-month and long-term perspectives. The sensitivity analyses indicated that the long-term, but not the short-term, findings were robust for different assumptions and changes in parameter estimates, resulting in ICERs similar to those of the base case scenario.

CONCLUSIONS

Offering dance and yoga to young girls with FAPDs generates small QALY gains and monetary savings compared with standard healthcare and is likely cost-effective. These findings make a valuable contribution to an area where evidence-based and cost-effective treatment interventions are needed.

CLINICAL TRIALS REGISTRATION NUMBER

ClinicalTrials.gov identifier: NCT02920268; Name: Just in TIME-Intervention With Dance and Yoga for Girls With Recurrent Abdominal Pain.

Economic evaluation of interventions for treatment-resistant depression: A systematic review

Background

The extraordinarily high prevalence of treatment-resistant depression (TRD), coupled with its high economic burden to both healthcare systems and society, underscore how critical it is that resources are managed optimally to address the significant challenge it presents.

Objective

To review the literature on economic evaluation in TRD systematically, with the aim of informing future studies by identifying key challenges specific to the area, and highlighting good practices.

Methods

A systematic literature search across seven electronic databases was conducted to identify both within-trial and model-based economic evaluations in TRD. Quality of reporting and study design was assessed using the Consensus Health Economic Criteria (CHEC). A narrative synthesis was conducted.

Results

We identified 31 evaluations, including 11 conducted alongside a clinical trial and 20 model-based evaluations. There was considerable heterogeneity in the definition of treatment-resistant depression, although with a trend for more recent studies to use a definition of inadequate response to two or more antidepressive treatments. A broad range of interventions were considered, including non-pharmacological neuromodulation, pharmacological, psychological, and service-level interventions. Study quality as assessed by CHEC was generally high. Frequently poorly reported items related to discussion of ethical and distributional issues, and model validation. Most evaluations considered comparable core clinical outcomes - encompassing remission, response, and relapse. There was good agreement on the definitions and thresholds for these outcomes, and a relatively small pool of outcome measures were used. Resource criteria used to inform the estimation of direct costs, were reasonably uniform. Predominantly, however, there was a high level of heterogeneity in terms of evaluation design and sophistication, quality of evidence used (particularly health state utility data), time horizon, population considered, and cost perspective.

Conclusion

Economic evidence for interventions in TRD is underdeveloped, particularly so for service-level interventions. Where evidence does exist, it is hampered by inconsistency in study design, methodological quality, and availability of high quality long-term outcomes evidence. This review identifies a number of key considerations and challenges for the design of future economic evaluations. Recommendations for research and suggestions for good practice are made.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=259848&VersionID=1542096, identifier CRD42021259848.

Watching the grass grow: does recreational cannabis legalization affect retail and agricultural wages?

Background

Over the past several years, cannabis has become legal for recreational use in many US states and jurisdictions around the world. The opening of these markets has led to the establishment of hundreds of cannabis production and retail firms with accompanying demand for labor, leading to concerns about spillover effects on wages from incumbents.

Methods

We study the markets for agricultural and retail labor in Washington and Colorado from 2000 to 2019 using differences-in-differences with synthetic controls. We employ employment data from the Quarterly Census of Employment and Wages, state-level demographic data from the US Census Bureau, and agricultural data from the National Agricultural Statistics Service. We use the least absolute shrinkage and selection operator (LASSO) for variable selection and classification and regression trees (CART) for chained imputation of missing values.

Results

We find little-to-no evidence of a significant difference in weekly wages per worker generated by cannabis legalization: the log of the weekly wage per worker decreases by 0.013 in Washington’s agricultural sector (p value 0.091) and increases by 0.059 in Washington’s retail sector (p value 0.606). Results in Colorado are qualitatively similar. These results are limited in part by the short post-legalization period of the data.

Conclusions

Cannabis legalization is unlikely to negatively impact incumbent agriculture or retail firms through the labor market channel.

A Scoping Review of Item-Level Missing Data in Within-Trial Cost-Effectiveness Analysis

OBJECTIVES

Cost-effectiveness analysis (CEA) alongside randomized controlled trials often relies on self-reported multi-item questionnaires that are invariably prone to missing item-level data. The purpose of this study is to review how missing multi-item questionnaire data are handled in trial-based CEAs.

METHODS

We searched the National Institute for Health Research journals to identify within-trial CEAs published between January 2016 and April 2021 using multi-item instruments to collect costs and quality of life (QOL) data. Information on missing data handling and methods, with a focus on the level and type of imputation, was extracted.

RESULTS

A total of 87 trial-based CEAs were included in the review. Complete case analysis or available case analysis and multiple imputation (MI) were the most popular methods, selected by similar numbers of studies, to handle missing costs and QOL in base-case analysis. Nevertheless, complete case analysis or available case analysis dominated sensitivity analysis. Once imputation was chosen, missing costs were widely imputed at item-level via MI, whereas missing QOL was usually imputed at the more aggregated time point level during the follow-up via MI.

CONCLUSIONS

Missing costs and QOL tend to be imputed at different levels of missingness in current CEAs alongside randomized controlled trials. Given the limited information provided by included studies, the impact of applying different imputation methods at different levels of aggregation on CEA decision making remains unclear.

Cost-effectiveness of a structured medication review approach for multimorbid older adults: Within-trial analysis of the OPERAM study

Background

Inappropriate polypharmacy has been linked with adverse outcomes in older, multimorbid adults. OPERAM is a European cluster-randomized trial aimed at testing the effect of a structured pharmacotherapy optimization intervention on preventable drug-related hospital admissions in multimorbid adults with polypharmacy aged 70 years or older. Clinical results of the trial showed a pattern of reduced drug-related hospital admissions, but without statistical significance. In this study we assessed the cost-effectiveness of the pharmacotherapy optimisation intervention.

Methods

We performed a pre-planned within-trial cost-effectiveness analysis (CEA) of the OPERAM intervention, from a healthcare system perspective. All data were collected within the trial apart from unit costs. QALYs were computed by applying the crosswalk German valuation algorithm to EQ-5D-5L-based quality of life data. Considering the clustered structure of the data and between-country heterogeneity, we applied Generalized Structural Equation Models (GSEMs) on a multiple imputed sample to estimate costs and QALYs. We also performed analyses by country and subgroup analyses by patient and morbidity characteristics.

Results

Trial-wide, the intervention was numerically dominant, with a potential cost-saving of CHF 3’588 (95% confidence interval (CI): -7’716; 540) and gain of 0.025 QALYs (CI: -0.002; 0.052) per patient. Robustness analyses confirmed the validity of the GSEM model. Subgroup analyses suggested stronger effects in people at higher risk.

Conclusion

We observed a pattern towards dominance, potentially resulting from an accumulation of multiple small positive intervention effects. Our methodological approaches may inform other CEAs of multi-country, cluster-randomized trials facing presence of missing values and heterogeneity between centres/countries.

Efficacy, cost-minimization, and budget impact of a personalized discharge letter for basal cell carcinoma patients to reduce low-value follow-up care

Background

The incidence of keratinocyte carcinomas is high and rapidly growing. Approximately 80% of keratinocyte carcinomas consist of basal cell carcinomas (BCC) with 50% of these being considered as low-risk tumors. Nevertheless, 83% of the low-risk BCC patients were found to receive more follow-up care than recommended according to the Dutch BCC guideline, which is one visit post-treatment for this group. More efficient management could reduce unnecessary follow-up care and related costs.

Objectives

To study the efficacy, cost-utility, and budget impact of a personalized discharge letter for low-risk BCC patients compared with usual care (no personalized letter).

Methods

In a multi-center intervention study, a personalized discharge letter in addition to usual care was compared to usual care in first-time BCC patients. Model-based cost-utility and budget impact analyses were conducted, using individual patient data gathered via surveys. The outcome measures were number of follow-up visits, costs and quality adjusted life years (QALY) per patient.

Results

A total of 473 first-time BCC patients were recruited. The personalized discharge letter decreased the number of follow-up visits by 14.8% in the first year. The incremental costs after five years were -€24.45 per patient. The QALYs were 4.12 after five years and very similar in both groups. The national budget impact was -€2,7 million after five years.

Conclusions

The distribution of a personalized discharge letter decreases the number of unnecessary follow-up visits and implementing the intervention in a large eligible population would results in substantial cost savings, contributing to restraining the growing BCC costs.

Patient-Reported Outcomes and Patient-Reported Experience of Patients With Atrial Fibrillation in the IMPACT-AF Clinical Trial

Background

The IMPACT‐AF (Integrated Management Program Advancing Community Treatment of Atrial Fibrillation) trial is a prospective, randomized, cluster design trial comparing atrial fibrillation management with a computerized clinical decision support system with usual care (control) in the primary care setting of Nova Scotia, Canada. The objective of this analysis was to assess and compare patient‐reported health‐related quality of life and patient‐reported experience with atrial fibrillation care between clinical decision support and control groups.

Methods and Results

Health‐related quality of life was measured using the EuroQol 5‐dimensional 5‐level scale, whereas patient‐reported experience was assessed using a self‐administered satisfaction questionnaire, both assessed at baseline and 12 months. Health utilities were calculated using the Canadian EuroQol 5‐dimensional 5‐level value set. Descriptive statistics and generalized estimating equations were used to compare between groups. Among 1145 patients enrolled in the trial, 717 had complete EuroQol 5‐dimensional 5‐level data at baseline. The mean age of patients was 73.53 years, and 61.87% were men. Mean utilities at baseline were 0.809 (SD, 0.157) and 0.814 (SD, 0.157) for clinical decision support and control groups, respectively. At baseline, most patients in both groups reported being “very satisfied” with the care received for their atrial fibrillation. There were no statistically significant differences in utility scores or patient satisfaction between groups at 12 months.

Conclusions

Health‐related quality of life of patients remained stable over 12 months, and there was no significant difference in patient satisfaction or utility scores between clinical decision support and control groups.

Registration information

clinicaltrials.gov. Identifier: NCT01927367.