Limitations of Minimal Clinically Important Difference Estimates and Potential Alternatives

Performance of baseline quartile-stratified minimal clinically important difference estimates was superior to individual minimal clinically important difference estimates when compared with a gold standard comparator of important change

ABSTRACT

A variety of minimal clinically important difference (MCID) estimates are available to distinguish subgroups with differing outcomes. When a true gold standard is absent, latent class growth curve analysis (LCGC) has been proposed as a suitable alternative for important change. Our purpose was to evaluate the performance of individual and baseline quartile-stratified MCIDs. The current study included data from 346 persons with baseline and 12-month postoperative outcome data from KASTPain, a no-effect randomized clinical trial conducted on persons with knee arthroplasty and pain catastrophizing. Subgroup trajectories from LCGC were used as a gold standard comparator. Minimal clinically important difference-specific trajectories of recovery were calculated for the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain, Disability and EuroQol-5 Dimension Visual Analogue Scale of self-reported health. The latent Kappa (K l ) chance-corrected agreement between MCIDs and LCGCs were estimated to indicate which MCID method was best at detecting important change. For all 3 outcomes, the average latent class probabilities ranged from 0.90 to 0.99, justifying the use of LCGCs as a gold standard. The K l for LCGC and individual MCIDs ranged from 0.21 (95% CI = 0.13, 0.28) to 0.52 (95% CI = 0.41, 0.66). Baseline quartile-stratified K l for WOMAC Pain and Disability were 0.85 (95% CI = 0.78, 0.92) and 0.74 (95% CI = 0.68, 0.83), respectively. Classification errors in individual MCID estimates most likely result from ceiling effects. Minimal clinically important differences calculated for each baseline quartile are superior to individually calculated MCIDs and should be used when latent class methods are not available. Use of individual MCIDs likely contribute substantial error and are discouraged for clinical application.

Long-Term Outcomes of Vagus Nerve Stimulation Paired With Upper Extremity Rehabilitation After Stroke

BACKGROUND

Persistent upper extremity (UE) impairment is common after stroke. Durable treatment benefits for chronic ischemic stroke are needed. The purpose of this report is to determine the long-term effects of vagus nerve stimulation paired with rehabilitation on impairment, activity, and participation in people with UE impairment after ischemic stroke.

METHODS

This is a post hoc analysis of data from the VNS-REHAB (A Pivotal Randomized Study Assessing Vagus Nerve Stimulation [VNS] During Rehabilitation for Improved Upper Limb Motor Function After Stroke) randomized clinical trial. Here, we report unblinded, partial crossover, and pooled 1-year outcomes. Initially, 108 participants across 19 sites with chronic ischemic stroke and moderate-to-severe UE impairment were enrolled in VNS-REHAB. Participants received 18 sessions of in-clinic intensive task-specific rehabilitation and 3 months of self-initiated home-based exercise with either real (active) or sham (control) vagus nerve stimulation. Thereafter, Control participants crossed over to receive in-clinic therapy paired with active stimulation. All participants performed home-based exercises paired with self-initiated active stimulation for 1 year. The Fugl-Meyer Assessment UE, Wolf Motor Function Test, and participation outcomes were assessed through 12 months.

RESULTS

Seventy-four participants (69%; 51 male; age, mean±SD, 59.6±8.9) completed 1-year follow-up and provided pooled data through 1 year. At 1 year, compared with baseline, there were improvements in impairment (Fugl-Meyer Assessment UE, 5.23 [95% CI, 4.08-6.39]; P<0.001) activity (Wolf Motor Function Test, 0.50 [95% CI, 0.41-0.59]; P<0.001) and patient-reported outcomes (Motor Activity Log-Quality of Movement: 0.64 [95% CI, 0.46-0.82], P<0.001; Motor Activity Log-Amount of Use: 0.64 [95% CI, 0.46-0.82], P<0.001; Stroke Impact Scale-Activities of Daily Living: 7.43 [95% CI, 5.09-9.77], P<0.001; Stroke Impact Scale-Hand: 17.89 [95% CI, 14.16-21.63], P<0.001; EQ-5D: 5.76 [95% CI, 2.08-9.45], P<0.05; and Stroke Specific-Quality of Life: 0.29 [95% CI, 0.19-0.39], P<0.001) compared with baseline.

CONCLUSIONS

People treated with paired vagus nerve stimulation maintained improvements in UE impairment, activity, participation, and quality-of-life measures at 1 year. Paired vagus nerve stimulation is a Food and Drug Administration-approved, beneficial treatment option for long-term benefit in individuals with chronic UE limitations after ischemic stroke.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03131960.

The measurement of "high-impact chronic pain": Limitations and alternative methods

OBJECTIVE

Chronic pain is known to be an important construct in clinical practice and a particular form of chronic pain, high-impact chronic pain (HICP), has gained recent interest and attention by pain clinicians, epidemiologists, and clinical researchers. The purpose of our Topical Review is to describe the historical development of measures of HICP and to explore the psychometric properties of HICP as well as to present alternative measurement methods.

METHODS

We identified strengths and weaknesses of the psychometric characteristics of HICP measures. Limitations of existing HICP measures were discussed and summarized and alternatives to current methods were proposed.

RESULTS

HICP operational definitions show variability across studies. All definitions cannot be correct, but which ones are incorrect cannot be determined as there is no gold standard. Random measurement error and recall bias are among the other limitations of current HICP measures. Model-based definitions of HICP, the discrete (for epidemiologic applications) and continuous (for clinical applications) latent variable models are discussed as likely superior alternatives to current methods.

CONCLUSIONS

Limitations of existing HICP methods are discussed and alternative development approaches to HICP measures are presented. The use of either discrete or continuous latent variable models would improve upon the psychometric characteristics of current HICP evidence. Examples are used to illustrate the benefits of latent variable models over traditional observed variable conceptualizations as the measurement of HICP continues to develop.

SIGNIFICANCE STATEMENT

This work takes the position that current methods of measuring high impact chronic pain (HICP) likely contain substantial error. We have endorsed an alternative approach for several psychometrically grounded reasons. We recommend that future work consider the discrete latent variable framework for dichotomous measures of HICP and the continuous latent variable framework for continuous measures of HICP. The paper provides illustrative examples of these methods for a different patient reported measure that is lacking a gold standard, much like HICP measures.

Early Improvements with Guselkumab Associate with Sustained Control of Psoriatic Arthritis: Post hoc Analyses of Two Phase 3 Trials

INTRODUCTION

Patterns of treatment response can inform clinical decision-making. This study assessed the course and impact of achieving minimal clinically important improvement (MCII) in clinical measures and patient-reported outcomes (PROs) with guselkumab in patients with active psoriatic arthritis (PsA).

METHODS

Post hoc analyses evaluated 1120 patients with PsA receiving guselkumab every 4 or 8 weeks (Q4W/Q8W) or placebo from DISCOVER-1 (31% tumor necrosis factor inhibitor-experienced) and DISCOVER-2 (biologic-naïve). Achievement of MCII in clinical Disease Activity Index for PsA (cDAPSA), patient global assessment (PtGA) of arthritis, PtGA of psoriasis, patient-reported pain, Functional Assessment of Chronic Illness Therapy-Fatigue, Health Assessment Questionnaire-Disability Index, 36-item Short-Form Health Survey Physical Component Summary score, PtGA Arthritis + Psoriasis, and PsA Disease Activity Score (PASDAS) was compared between the guselkumab and placebo groups using Cox regression. Logistic regression adjusting for baseline factors evaluated associations between early (W4/W8) MCII achievement and stringent response (≥%50/%70 improvement in American College of Rheumatology response criteria, cDAPSA low disease activity [LDA], PASDAS LDA, and minimal disease activity) at W24/W52 among guselkumab-randomized patients.

RESULTS

Among patients with highly active PsA (baseline cDAPSA = 44.1-45.0, PASDAS = 6.4-6.5), times to MCII were significantly faster for guselkumab vs. placebo (hazard ratios 1.3-2.5; P < 0.05). Across measures, at first timepoint assessed, MCII rates were significantly higher with guselkumab (Q4W/Q8W 28-68%/29-65%) vs. placebo (19-47%; both P < 0.05). Early (W4/W8) MCII with guselkumab associated with higher odds of achieving stringent responses at W24/W52 (odds ratios 1.4-17.2/1.4-5.4).

CONCLUSIONS

In a mixed PsA population, significant proportions of patients treated with guselkumab achieved early (W4/W8) MCII across clinical and PRO measures, which associated with a higher likelihood of attaining clinically relevant improvements and low levels of disease activity at W24/W52.

TRIAL REGISTRATION

DISCOVER-1 (NCT03162796). DISCOVER-2 (NCT03158285).

Minimal clinically important difference for acupuncture for patients with chronic spontaneous urticaria: secondary analysis from a multicentre randomised controlled trial in China

OBJECTIVES

To evaluate the minimal clinically important difference (MCID) value for acupuncture treatment in chronic spontaneous urticaria (CSU), providing guidance for its application in CSU management.

DESIGN

Secondary analysis of data from a multicentre randomised controlled trial.

SETTING

Three tertiary hospitals across three cities in China.

PARTICIPANTS

103 CSU patients (78.7% female) with an average age of 39.97 years.

INTERVENTIONS

Participants received acupuncture treatment for 4 weeks in the original study.

OUTCOME MEASURES

MCID and minimal detectable change (MDC) for the Urticaria Activity Score over 7 days (UAS7) in acupuncture treatment of CSU. Convergent validity assessed by intraclass correlation coefficient (ICC). Responsiveness evaluated through Spearman correlation between UAS7 improvements and anchor tools (physician's and patient's assessments). MDC calculated using SE of measurement of changes in UAS7 scores. MCID estimated using distribution-based and anchor-based methods.

RESULTS

The ICC for UAS7 was 0.86. Improvements in UAS7 scores were significantly correlated with patient (r=0.44, p<0.01) and physician (r=0.85, p<0.01) assessments of CSU activity shifts. The MDC for UAS7 was 5.08. The MCID for acupuncture treatment in CSU was 8.3.

CONCLUSIONS

This study provides the first MCID value for acupuncture treatment in CSU. These findings contribute to the understanding of acupuncture's effects in treating CSU and may inform future research and clinical practice in the management of this condition.

TRIAL REGISTRATION NUMBER

ChiCTR1900022994.