Validating and assessing the sensitivity of the Health Assessment Questionnaire-Disability Index-derived Short Form-6D in patients with early aggressive rheumatoid arthritis

Secular changes in functional disability, pain, fatigue and mental well-being in early rheumatoid arthritis. A longitudinal meta-analysis

OBJECTIVES

To conduct a systematic review and longitudinal meta-analysis of early rheumatoid arthritis (RA) cohorts with long-term data on pain, fatigue or mental well-being.

METHODS

Searches using PUBMED, EMBASE and PyscInfo were performed to identify all early RA cohorts with longitudinal measures of pain, fatigue or mental well-being, along with clinical measures. Using longitudinal meta-analyses, the progression of each outcome over the first 60-months was estimated. Cohorts were stratified based on the median recruitment year to investigate secular trends in disease progression.

RESULTS

Of 7,319 papers identified, 75 met the inclusion criteria and 46 cohorts from 41 publications provided sufficient data on 18,046 patients for meta-analysis. The Disease Activity Scores (DAS28) and the Short-Form 36 (SF-36) Physical Component Score (PCS) indicated that post-2002 cohorts had statistically significant improvements over the first 60-months compared to pre-2002 cohorts, with standardised mean differences (SMD) of 0.86 (95% Confidence Intervals 0.34 to 1.37) and 0.76 (95% CI 0.25 to 1.27) respectively at month-60. However, post-2002 cohorts indicated statistically non-significant improvements in pain, fatigue, functional disability and SF-36 Mental Component Score (MCS) compared to pre-2002 cohorts, with SMD of 0.24 (95% CI -0.25 to 0.74), 0.38 (95% CI -0.11 to 0.88), 0.34 (95% CI -0.15-0.84) and -0.08 (95% CI -0.41 to 0.58) at month-60 respectively.

CONCLUSIONS

Recent cohorts indicate improved levels of disease activity and physical quality of life, however this has not translated into similar improvements in levels of pain, fatigue and functional disability by 60-months.

Item response theory, computerized adaptive testing, and PROMIS: assessment of physical function

OBJECTIVE

Patient-reported outcome (PRO) questionnaires record health information directly from research participants because observers may not accurately represent the patient perspective. Patient-reported Outcomes Measurement Information System (PROMIS) is a US National Institutes of Health cooperative group charged with bringing PRO to a new level of precision and standardization across diseases by item development and use of item response theory (IRT).

METHODS

With IRT methods, improved items are calibrated on an underlying concept to form an item bank for a "domain" such as physical function (PF). The most informative items can be combined to construct efficient "instruments" such as 10-item or 20-item PF static forms. Each item is calibrated on the basis of the probability that a given person will respond at a given level, and the ability of the item to discriminate people from one another. Tailored forms may cover any desired level of the domain being measured. Computerized adaptive testing (CAT) selects the best items to sharpen the estimate of a person's functional ability, based on prior responses to earlier questions. PROMIS item banks have been improved with experience from several thousand items, and are calibrated on over 21,000 respondents.

RESULTS

In areas tested to date, PROMIS PF instruments are superior or equal to Health Assessment Questionnaire and Medical Outcome Study Short Form-36 Survey legacy instruments in clarity, translatability, patient importance, reliability, and sensitivity to change.

CONCLUSION

Precise measures, such as PROMIS, efficiently incorporate patient self-report of health into research, potentially reducing research cost by lowering sample size requirements. The advent of routine IRT applications has the potential to transform PRO measurement.

Longitudinal predictive ability of mapping models: examining post-intervention EQ-5D utilities derived from baseline MHAQ data in rheumatoid arthritis patients

OBJECTIVES

The purpose of this methodological study was to to provide insight into the under-addressed issue of the longitudinal predictive ability of mapping models. Post-intervention predicted and reported utilities were compared, and the effect of disease severity on the observed differences was examined.

METHODS

A cohort of 120 rheumatoid arthritis (RA) patients (60.0% female, mean age 59.0) embarking on therapy with biological agents completed the Modified Health Assessment Questionnaire (MHAQ) and the EQ-5D at baseline, and at 3, 6 and 12 months post-intervention. OLS regression produced a mapping equation to estimate post-intervention EQ-5D utilities from baseline MHAQ data. Predicted and reported utilities were compared with t test, and the prediction error was modeled, using fixed effects, in terms of covariates such as age, gender, time, disease duration, treatment, RF, DAS28 score, predicted and reported EQ-5D.

RESULTS

The OLS model (RMSE = 0.207, R(2) = 45.2%) consistently underestimated future utilities, with a mean prediction error of 6.5%. Mean absolute differences between reported and predicted EQ-5D utilities at 3, 6 and 12 months exceeded the typically reported MID of the EQ-5D (0.03). According to the fixed-effects model, time, lower predicted EQ-5D and higher DAS28 scores had a significant impact on prediction errors, which appeared increasingly negative for lower reported EQ-5D scores, i.e., predicted utilities tended to be lower than reported ones in more severe health states.

CONCLUSIONS

This study builds upon existing research having demonstrated the potential usefulness of mapping disease-specific instruments onto utility measures. The specific issue of longitudinal validity is addressed, as mapping models derived from baseline patients need to be validated on post-therapy samples. The underestimation of post-treatment utilities in the present study, at least in more severe patients, warrants further research before it is prudent to conduct cost-utility analyses in the context of RA by means of the MHAQ alone.

Performance of an item response theory-based computer adaptive test in identifying functional decline

OBJECTIVE

To achieve a low respondent burden and increase the responsiveness of functional measurement by using an item response theory-based computer adaptive test (CAT), the Activity Measure for Post-Acute Care (AM-PAC) CAT.

DESIGN

Two-year prospective cohort study.

SETTING

Telephonic assessments from a quaternary medical center.

PARTICIPANTS

Patients (N=311) with late-stage lung cancer (LC).

INTERVENTIONS

Monthly assessments for up to 2 years. Disease progression was determined via record abstraction. Anchor-based responsiveness techniques were used to compare AM-PAC-CAT score changes between global rating of change (GRC) question response levels, as well as between intervals when adverse clinical events or symptom worsening did and did not occur. Distribution-based responsiveness assessments included calculation of the standardized effect size (SES) and standardized response mean (SRM).

MAIN OUTCOME MEASURES

AM-PAC-CAT, symptom numerical rating scales, and a GRC.

RESULTS

Administration time averaged 112 seconds over 2543 interviews. AM-PAC-CAT score changes became more positive as GRC responses reflected more improved states: a lot worse (-11.62), a little worse (-1.92), the same (-.10), a little better (1.01), and a lot better (2.82). Score changes were negative when associated with adverse clinical events. The SES and SRM for score differences between 1 to 2 and 9 to 10 months prior to death were -.87 and -1.13, respectively. The minimally important difference estimate was defined by the mean CAT session SE at 2.0.

CONCLUSIONS

The AM-PAC-CAT imposes a low, <2-minute, respondent burden, and distribution- and anchor-based methods suggest that is moderately responsive in patients with late-stage LC.

Scale Characteristics and Mapping Accuracy of the US EQ-5D, UK EQ-5D, and SF-6D in Patients with Rheumatoid Arthritis

Objective.

To compare the US EQ-5D with the UK EQ-5D and the SF-6D in patients with rheumatoid arthritis (RA). To provide mappings for each of the scales based on clinical variables.

Methods.

We studied 12,424 patients with RA with 66,958 longitudinal observations using linear regression. In our mapping models we used the Health Assessment Questionnaire (HAQ) as a continuous predictor variable and as individual items. More complex models included the addition of a visual analog pain scale, the mood scale from the SF-36, and demographic and comorbidity covariates. We compared various models using root mean squared error (RMSE), in-sample and out-of-sample mean absolute error (MAE), and other measures of prediction accuracy and model fit.

Results.

At any level of clinical severity, the US EQ-5D always had a higher utility score than the UK EQ-5D; and overall, the US scores were 0.094 units higher. The best models explained 64% to 72% of variance in utility scores, with RMSE values of 0.07 (SF-6D), 0.11 (EQ-5D US), and 0.17 (UK EQ-5D). There was a substantial increase in predictive accuracy by using pain and mood as predictor variables in the mapping.

Conclusion.

The US EQ-5D differs from the UK version and from the SF-6D in mean scores and ranges. When determined by mapping, the US EQ-5D has a much lower prediction error than the UK EQ-5D. Simple mapping models that use HAQ and pain have acceptable error rates, although more complex models that include mood scores and individual HAQ items substantially improve predictive accuracy.

Exploring the validity of estimating EQ-5D and SF-6D utility values from the health assessment questionnaire in patients with inflammatory arthritis

Background

Utility scores are used to estimate Quality Adjusted Life Years (QALYs), applied in determining the cost-effectiveness of health care interventions. In studies where no preference based measures are collected, indirect methods have been developed to estimate utilities from clinical instruments. The aim of this study was to evaluate a published method of estimating the EuroQol-5D (EQ-5D) and Short Form-6D (SF-6D) (preference based) utility scores from the Health Assessment Questionnaire (HAQ) in patients with inflammatory arthritis.

Methods

Data were used from 3 cohorts of patients with: early inflammatory arthritis (<10 weeks duration); established (>5 years duration) stable rheumatoid arthritis (RA); and RA being treated with anti-TNF therapy. Patients completed the EQ-5D, SF-6D and HAQ at baseline and a follow-up assessment. EQ-5D and SF-6D scores were predicted from the HAQ using a published method. Differences between predicted and observed EQ-5D and SF-6D scores were assessed using the paired t-test and linear regression.

Results

Predicted utility scores were generally higher than observed scores (range of differences: EQ-5D 0.01 - 0.06; SF-6D 0.05 - 0.10). Change between predicted values of the EQ-5D and SF-6D corresponded well with observed change in patients with established RA. Change in predicted SF-6D scores was, however, less than half of that in observed values (p < 0.001) in patients with more active disease. Predicted EQ-5D scores underestimated change in cohorts of patients with more active disease.

Conclusion

Predicted utility scores overestimated baseline values but underestimated change. Predicting utility values from the HAQ will therefore likely underestimate the QALYs of interventions, particularly for patients with active disease. We recommend the inclusion of at least one preference based measure in future clinical studies.