Challenges Associated with Estimating Minimal Clinically Important Differences in COPD—The NHLBI Perspective

Baseline dependent minimally important differences for clinical outcomes of pulmonary rehabilitation in people with COPD

INTRODUCTION

Minimally important differences (MIDs) for common outcomes of pulmonary rehabilitation are well documented for people with chronic obstructive pulmonary disease (COPD). It is not known whether MIDs differ based on COPD disease characteristics. This study aimed to estimate MIDs for clinical outcomes of pulmonary rehabilitation dependent upon baseline characteristics.

METHODS

A database containing 2791 people with COPD was split into derivation (n=2245; age 66±9 years; 50% males; FEV1 47±20% predicted) and comparator (n=546; age 66±9 years; 47% males; FEV1 46±21% predicted) cohorts. MIDs were estimated using 0.5 x SD (symmetrically distributed) or 0.5 x IQR (non-symmetrically distributed) for: 6-minute walk test (6MWT), constant work rate test (CWRT), COPD assessment test (CAT), St. George's respiratory questionnaire (SGRQ), hospital anxiety and depression scale (HADS), and fat-free mass index (FFMI). MIDs were estimated based on baseline outcome scores, lung function, modified medical research council (mMRC) grade and FFMI.

RESULTS

MID estimates were comparable to previously reported values. MIDs for SGRQ domains (Symptom=8.7 points, Activity=7.1 points, Impact=8.1 points) and FFMI were produced (0.36kg/m2). There was greater variation of change in 6MWT, SGRQ-activity, SGRQ-impact, HADS and FFMI on which the MIDs were determined when categorising for baseline values (all, p<0.05). Greater variation of change in 6MWT on which the MIDs were determined was evident with COPD disease severity grouping (p<0.05). The magnitude of change in 6MWT, CAT, CWRT, SGRQ-activity, and FFMI with baseline mMRC score categorisation resulted in greater variation on which the MIDs were determined (all, p<0.05). Baseline stratification for FFMI resulted in greater variation of change in CWRT (p<0.001) and HADS-depression (p = 0.043) on which MIDs were determined.

DISCUSSION

Findings suggest that baseline presentation should be considered for people with COPD when assessing the efficacy of pulmonary rehabilitation. However, clinical significance of the variation underpinning MIDs is yet to be determined.

269th ENMC international workshop: 10 years of clinical trials in Duchenne muscular dystrophy - What have we learned? 9-11 December 2022, Hoofddorp, The Netherlands

There are multiple avenues for therapeutic development in Duchenne muscular dystrophy (DMD), which are highlighted in the first section of this report for the "10 years of Clinical trials in DMD - What have we learned?" workshop. This report then provides an overview of the presentations made at the workshop grouped into the following core themes: trial outcomes, disease heterogeneity, meaningfulness of outcomes and the utility of real-world data in trials. Finally, we present the consensus that was achieved at the workshop on the learning points from 10 years of clinical trials in DMD, and possible action points from these. This includes further work in expanding the scope and range of trial outcomes and assessing the efficacy of new trial structures for DMD. We also highlight several points which should be addressed during future interactions with regulators, such as clinical meaningfulness and the use of real-world data.

Impact of Lung Function and Exacerbations on Health-Related Quality of Life in COPD Patients Within One Year: Real-World Analysis Based on Claims Data

PURPOSE

Real-world evidence on the impact of forced expiratory volume in one second (FEV1) and exacerbations on health-related quality of life (HRQoL) in patients with chronic obstructive pulmonary disease (COPD) is sparse especially with regard to GOLD ABCD groups. This study investigates how changes in FEV1 and exacerbations affect generic and disease-specific HRQoL in COPD patients over one year.

METHODS

Using German claims data and survey data, we classified 3016 COPD patients and analyzed their health status by GOLD groups AB and CD. HRQoL was measured with the disease-specific COPD assessment test (CAT) and the visual analog scale (VAS) from the generic Euro-Qol 5D-5L. We applied change score models to assess associations between changes in FEV1 (≥100 mL decrease/no change/≥100 mL increase) or the development of severe exacerbations with change in HRQoL.

RESULTS

FEV1 decrease was associated with a significant but not minimal important difference (MID) deterioration in disease-specific HRQoL (mean change [95% CI]: CAT +0.74 [0.15 to 1.33]), while no significant change was observed in the generic VAS. Experiencing at least one severe exacerbation also had a significant impact on CAT deterioration (+1.58 [0.52 to 2.64]), but again not on VAS. Here, GOLD groups AB showed not only a statistically but also a clinically relevant MID deterioration in CAT (+2.1 [0.88 to 3.32]). These particular patient groups were further characterized by a higher probability of being male, having a higher mMRC and Charlson index, and a lower probability of having higher FEV1 or BMI values.

CONCLUSION

FEV1 decline and the occurrence of ≥1 severe exacerbation are significantly associated with overall deterioration in disease-specific HRQoL. Preventing severe exacerbations particularly in patients without previous severe exacerbations (ABCD groups A and B) may help to stabilize the key patient-reported outcome HRQoL.

The effect of pulmonary rehabilitation on physical performance and health related quality of life in patients with chronic lung disease

Pulmonary rehabilitation (PR) is a multidisciplinary approach that improves exercise capacity and health-related quality of life in patients with chronic lung disease. We retrospectively reviewed the medical records of the patients with chronic lung disease who participated in the PR program at University Medical Center in Lubbock, Texas, between 2014 and 2019. Clinical information, 6-min walk test (6 MW T) results, the number of emergency department (ED) visits and hospitalizations, and psychosocial questionnaires (CAT score, PHQ9 and mMRC dyspnea score) were recorded before and after the completion of the program. Multiple variable linear regression and logistic regression were used to analyze the relationships between patient characteristics and changes in the 6-min walk distance and the achievement of a minimal clinically important differences (MCID) in the 6-min walk distance, the CAT score, the PHQ-9, and the mMRC. 279 patients enrolled in pulmonary rehabilitation; 144 patients (52%) completed the program. After completion of the program, 84 patients increased their 6 MW T distance to exceed the MCID with a mean increase of 178 feet, and the number of ED visits and hospitalizations decreased from 0.80 ± 1.11 to 0.55 ± 0.87 (p < 0.05) in the six months before and after rehabilitation. There were statistically significant improvements in all three psychosocial scores. Factors associated with non-completion included younger age, female gender, and shorter baseline 6 MW T distances. The MCID helps evaluate patient outcomes following pulmonary rehabilitation and provide more definite assessment of benefits. The high dropout rate indicates that programs must continuously monitor patient participation and interest.

The Minimal Clinical Important Difference (MCID) in Annual Rate of Change of Timed Function Tests in Boys with DMD

BACKGROUND

Duchenne muscular dystrophy (DMD) is a rare x-linked recessive genetic disorder affecting 1 in every 5000-10000 [1, 2]. This disease leads to a variable but progressive sequential pattern of muscle weakness that eventually causes loss of important functional milestones such as the ability to walk. With promising drugs in development to ameliorate the effects of muscle weakness, these treatments must be associated with a clinically meaningful functional change.

OBJECTIVE

The objective of this analysis is to determine both distribution, minimal detectable change (MDC), and anchor-based, minimal clinically important difference, (MCID) of 12 month change values in standardized time function tests (TFT) used to monitor disease progression in DMD.

METHOD

This is a retrospective analysis of prospectively collected data from a multi-center prospective natural history study with the Cooperative International Neuromuscular Research Group (CINRG). This study calculated MDC and MCID values for 3 commonly used timed function tests typically used to monitor disease progression; supine to stand (STS), 10 meter walk/run (10MWT), and 4 stair climb (4SC). MDC used standard error of measurement (SEM) while MCID measurements used the Vignos scale as an anchor to determine clinical change in functional status.

RESULTS

All 3 TFT were significantly important clinical endpoints to detect MDC and MCID changes. MDC and MCID 12 month changes were significant in 10MWT (-0.138, -0.212), Supine to Stand (-0.026, -0.023) and 4 stair climb (-0.034, -0.035) with an effect size greater or close to 0.2.

CONCLUSION

The 3 TFT are clinically meaningful endpoints used to establish change in DMD. MCID values were higher than MDC values indicating that an anchor-based approach using Vignos as a clinically meaningful loss of lower extremity abilities is appropriate to assess change in boys with DMD.

Responsiveness and minimal clinically important difference of the EQ-5D-5L in cervical intraepithelial neoplasia: a longitudinal study

Background

With the widespread clinical application of the five-level version of the EuroQol five-dimensional questionnaire (EQ-5D-5L), whether the questionnaire scores are responsive to changes in patients’ health and how much changes in questionnaire scores represent patients’ real health changes require consideration. Consequently, we assessed responsiveness and estimated the minimal clinically important difference (MCID) of the EQ-5D-5L in surgically treated patients with cervical intraepithelial neoplasia (CIN) to determine the relationship between MCID and minimal detectable change (MDC).

Methods

We conducted a longitudinal, observational study. Participants were patients with CIN from the gynecology inpatient department of a grade-A tertiary hospital in Shihezi, Xinjiang, China. Participants completed the EQ-5D-5L and the Global Rating of Change Questionnaire (GRCQ) at baseline and one month post-surgery. The Wilcoxon signed-rank test was used to compare EQ-5D-5L scores pre- and post-treatment. We calculated the effect size (ES) and the standardized response mean (SRM) to quantitatively assess responsiveness. Distribution-based, anchor-based, and instrument-defined methods were used to estimate MCID. MCID to MDC ratios at individual- and group-levels were also calculated.

Results

Fifty patients with CIN completed the follow-up investigation (mean age 44.76 ± 8.72 years; mean follow-up time 32.28 ± 1.43 days). The index value and EQ visual analogue scale (EQ VAS) of the EQ-5D-5L improved by 0.025 and 6.92 (all p < 0.05) at follow-up as compared to baseline respectively. The ES and the SRM of the index value were 0.47 and 0.42 respectively, indicating small responsiveness; while the ES and the SRM of EQ VAS were 0.50 and 0.49 respectively, indicating small to moderate responsiveness. The average (range) of MCIDs for index value and EQ VAS were 0.039 (0.023–0.064) and 5.35 (3.12–6.99) respectively. These values can only be used to determine whether patients have experienced clinically meaningful health improvements at the group level.

Conclusions

The EQ-5D-5L has only small to moderate responsiveness in post-surgical patients with CIN, and the MCIDs developed in this study can be used for group-level health assessment. However, further study is needed concerning health changes at the individual level.

The London Chest Activity of Daily Living scale cut-off point to discriminate functional status in patients with chronic obstructive pulmonary disease

OBJECTIVE

To determine the cut-off point for the London Chest Activity of Daily Living scale in order to better discriminate functional status. Secondarily, to determine which of the scores (total or %total) is better associated with clinical outcomes of a pulmonary rehabilitation program.

METHODS

Sixty-one patients with chronic obstructive pulmonary disease performed the following tests: spirometry; Chronic Obstructive Pulmonary Disease Assessment Test; Saint George's Respiratory Questionnaire; modified Medical Research Council, the body-mass index, airflow obstruction, dyspnea, and exercise capacity index; six-minute walk test; physical activity in daily life assessment and London Chest Activity of Daily Living scale. Thirty-eight patients were evaluated pre- and post-pulmonary rehabilitation . The cut-off point was determined using the receiver operating characteristic curve with six-minute walk test (cut-off point: 82%pred), modified Medical Research Council (cut-off point: 2), level of physical (in)activity (cut-off point: 80min per day in physical activity ≥3 metabolic equivalent of task) and presence/absence of severe physical inactivity (cut-off point: 4580 steps per day) as anchors.

RESULTS

A cut-off point found for all anchors was 28%: modified Medical Research Council [sensitivity=83%; specificity=72%; area under the curve=0.80]; level of physical (in)activity [sensitivity=65%; specificity=59%; area under the curve=0.67] and classification of severe physical inactivity [sensitivity=70%; specificity=62%; area under the curve=0.70]. The patients who scored ≤28% in %total score of London Chest Activity of Daily Living had lower modified Medical Research Council , Chronic Obstructive Pulmonary Disease Assessment Test, Saint George's Respiratory Questionnaire, body-mass index, airflow obstruction, dyspnea and exercise capacity index and sitting time than who scored >28%, and higher forced expiratory volume in the first second, time in physical activity ≥3 metabolic equivalent of task, steps per day and six-minute walk distance. The %total score of London Chest Activity of Daily Living correlated better with clinical outcomes than the total score.

CONCLUSIONS

The cut-off point of 28% is sensitive and specific to distinguish the functional status in patients with chronic obstructive pulmonary disease. The %total score of the London Chest Activity of Daily Living reflects better outcomes of chronic obstructive pulmonary disease when compared to total score.

Healthcare Professionals' Preferred Efficacy Endpoints and Minimal Clinically Important Differences in the Assessment of New Medicines for Chronic Obstructive Pulmonary Disease

BACKGROUND

Registration authorities evaluate effects of new medicines for chronic obstructive pulmonary disease (COPD) on airway obstruction, dyspnea, health status and exacerbations. To establish clinical relevance, minimal clinically important differences (MCIDs) are used. The aim of this study was to investigate which efficacy endpoints and MCIDs healthcare professionals consider clinically relevant for new COPD medicines.

MATERIALS AND METHODS

7,731 Healthcare professionals received an electronic questionnaire. Participants were asked for: 1) preferred efficacy endpoints for new COPD medicines and 2) cut-off values defining clinical relevance for forced expiratory volume in 1 sec (FEV1), Transition Dyspnea Index (TDI) and St. George's Respiratory Questionnaire (SGRQ). Those cut-off values were compared to the MCIDs used by registration authorities, namely 100 ml for FEV1, 1 unit for TDI and 4 units for SGRQ.

RESULTS

227 Healthcare professionals responded to the questionnaire. Most preferred efficacy endpoints were exacerbations (51.0%), airway obstruction (46.9%) and health status (44.9%). Mean cut-off values for TDI and SGRQ were significantly higher than the corresponding MCIDs, mean differences 1.5 (95%CI = 1.3-1.8, p < 0.001) and 7.0 (95%CI = 5.1-8.8, p < 0.001), respectively. The mean cut-off value for FEV1 was comparable to the MCID (mean difference 2.2, 95%CI = -19.9-24.3, p = 0.84).

CONCLUSIONS

Healthcare professionals largely agree with efficacy endpoints used for the evaluation of new COPD medicines. However, they seem to prefer higher cut-off values for clinical relevance for TDI and SGRQ than the registration authorities. Effects of new medicines on TDI and SGRQ that are considered clinically relevant by registration authorities do, therefore, not necessarily reflect healthcare professionals' perspectives on clinical relevance.

Approaches to outcome assessment in pulmonary rehabilitation

A comprehensive assessment is the foundation of a successful pulmonary rehabilitation programme. There is a broad selection of outcome measures that tend to be categorized into measures of exercise performance (including measures of strength) quality of life (health status), psychological well-being, nutritional status and more recently knowledge and self-efficacy. There is a growing interest in the measurement of physical activity too, although this is a current line of research activity. A sophisticated suite of outcomes allows the rehabilitation program to be personalised to the individual and deliver effective rehabilitation.

Minimal clinically important differences in pharmacological trials

The concept of a minimal clinically important difference (MCID) is well established. Here, we review the evidence base and methods used to define MCIDs as well as their strengths and limitations. Most MCIDs in chronic obstructive pulmonary disease (COPD) are empirically derived estimates applying to populations of patients. Validated MCIDs are available for many commonly used outcomes in COPD, including lung function (100 ml for trough FEV1), dyspnea (improvement of ≥ 1 unit in the Transition Dyspnea Index total score or 5 units in the University of California, San Diego Shortness of Breath Questionnaire), health status (reduction of 4 units in the St George's Respiratory Questionnaire total score), and exercise capacity (47.5 m for the incremental shuttle walking test, 45-85 s for the endurance shuttle walking test, and 46-105 s for constant-load cycling endurance tests), but there is currently no validated MCID for exacerbations. In a clinical trial setting, many factors, including study duration, withdrawal rate, baseline severity, and Hawthorne effects, can influence the measured treatment effect and determine whether it reaches the MCID. We also address recent challenges presented by clinical trials that compare active treatments and suggest that MCIDs should be used to identify the additional proportion of patients who benefit, for example, when one drug is replaced by another or when a second drug is added to a first. We propose the term "minimum worthwhile incremental advantage" to describe this parameter.

An official American Thoracic Society/European Respiratory Society statement: key concepts and advances in pulmonary rehabilitation

BACKGROUND

Pulmonary rehabilitation is recognized as a core component of the management of individuals with chronic respiratory disease. Since the 2006 American Thoracic Society (ATS)/European Respiratory Society (ERS) Statement on Pulmonary Rehabilitation, there has been considerable growth in our knowledge of its efficacy and scope.

PURPOSE

The purpose of this Statement is to update the 2006 document, including a new definition of pulmonary rehabilitation and highlighting key concepts and major advances in the field.

METHODS

A multidisciplinary committee of experts representing the ATS Pulmonary Rehabilitation Assembly and the ERS Scientific Group 01.02, "Rehabilitation and Chronic Care," determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant clinical and scientific expertise. The final content of this Statement was agreed on by all members.

RESULTS

An updated definition of pulmonary rehabilitation is proposed. New data are presented on the science and application of pulmonary rehabilitation, including its effectiveness in acutely ill individuals with chronic obstructive pulmonary disease, and in individuals with other chronic respiratory diseases. The important role of pulmonary rehabilitation in chronic disease management is highlighted. In addition, the role of health behavior change in optimizing and maintaining benefits is discussed.

CONCLUSIONS

The considerable growth in the science and application of pulmonary rehabilitation since 2006 adds further support for its efficacy in a wide range of individuals with chronic respiratory disease.

Biobehavioral measures as outcomes: a cautionary tale

This article discusses the use of biobehavioral measures as outcomes for health care intervention studies. Effect size (ES) values for salivary cortisol and observation-based measures of pain and agitation were examined. Effects pre to post treatment were assessed separately for nursing home residents with and without acute psychotic symptoms. This study revealed large positive effects on both pain and agitation measures in the group with acute psychotic symptoms and small-to-medium positive effects on these same measures in the group without acute psychotic symptoms. In both of these groups, the ES values were not consistently positive on the cortisol measures. Prior to determining whether a measure can be used to estimate minimum clinically important differences, it is essential to consider if the biomarker will be responsive to therapy in the populations and contexts being studied.

NVA237, a long-acting muscarinic antagonist, as an emerging therapy for chronic obstructive pulmonary disease

Bronchodilation with a long-acting muscarinic antagonist (LAMA) or long-acting β(2)-agonist is central to the management of chronic obstructive pulmonary disease (COPD). Tiotropium, the first LAMA available for use in COPD, has been shown to be an effective bronchodilator and is generally safe and well tolerated. However, tiotropium has limitations that include a high incidence of dry mouth, slow onset of action and, in some studies, a part of the patient population did not achieve clinically significant bronchodilation. It also remains unclear whether tiotropium reduces progressive deterioration of lung function in patients with COPD. An ideal LAMA would provide clinically meaningful bronchodilation, deliver symptom relief, prevent disease progression, improve exercise tolerance and health status, prevent and treat complications and exacerbations and reduce mortality risk. A 24-h duration of action, rapid onset of action and a good safety and tolerability profile are also desirable. The once-daily LAMA, NVA237 (glycopyrronium bromide), may meet some of these characteristics. NVA237 has high selectivity for the muscarinic type-3 (M(3)) receptor which might potentially result in a higher therapeutic index than tiotropium, which is less selective for M(3). Phase II studies showed that NVA237 once daily provides clinically significant 24-h bronchodilation with a rapid onset of action and a favourable safety and tolerability profile. Phase III studies are ongoing that will assess the long-term safety and efficacy of NVA237.

[Clinical value of forced expiratory volume in 1 s (FEV1) in chronic obstructive pulmonary disease]

There is overwhelming evidence from large-scale placebo-controlled trials but also from epidemiologic COPD (chronic obstructive pulmonary disease) studies and meta-analyses supporting FEV(1) (forced expiratory volume in 1 s) as a strong diagnostic and prognostic marker that predicts future morbidity and mortality. Specifically, attenuation of reduced FEV(1) is a powerful indicator of successful medical intervention and vice versa. FEV(1) decline indicates an increasing risk for advanced disease stage eventually leading to further deterioration. However, it remains to be determined whether reducing the frequency of exacerbations or pharmacological improvement of FEV(1) can help to slow lung function decline and consequently improve clinical outcome in these patients. All in all, FEV(1) and its change over time are essential parameters in the assessment of COPD progression and efficacy of therapeutic intervention.