Anchor-based Minimal Important Difference Research Articles

Establishing minimally important differences for the American Shoulder and Elbow Surgeons score and the Western Ontario Rotator Cuff Index in patients with full-thickness rotator cuff tears

The American Shoulder and Elbow Surgeons (ASES) score and the Western Ontario Rotator Cuff Index (WORC) are frequently used measures in clinical research for patients with rotator cuff tears (RCTs). The minimally important differences (MIDs) for these measures have not been established in patients with RCTs. The purpose of this study was to establish the MIDs for patients with known RCTs treated both surgically or nonsurgically. We included 222 subjects with full-thickness RCTs. The WORC and ASES were collected at baseline and at 4, 8, 16, 32, 48, and 64 weeks, as was an end of study form with questions about change in the condition after treatment. We calculated anchor-based and distribution-based MIDs. We used regression modeling to determine change in MIDs as predicted by several variables. For the anchor-based method, we found an MID of 21.9 for the ASES and -282.6 for the WORC. When using the distribution-based method of ½ and ⅓ the standard deviation, we arrived at an MID of 26.9 and 17.9 points for the ASES and -588.7 and -392.5 points for the WORC. No variables predicted MID changes. This is the first study to report MIDs for the ASES and WORC in a population of patients with only full-thickness RCTs. This information will directly improve our ability to determine when patients with RCTs are changing in a meaningful manner and accurately power clinical studies using these outcome measures.

Estimating minimally important differences for the PROMIS pain interference scales: results from 3 randomized clinical trials.

Minimally important difference (MID) refers to the smallest meaningful difference that carries implications for patient care. Minimally important differences are necessary to help interpret patient-reported pain outcomes in research and clinical practice. The PROMIS pain interference scales were validated across diverse samples; however, more information about their MIDs could improve their interpretability. The purpose of this study was to estimate MIDs for 4 fixed-length PROMIS pain interference scales, including the 6-item Pain Short Form and the 4-, 6-, and 8-item pain interference scales used in the PROMIS profile instruments. Data were analyzed from 3 randomized controlled trials (N = 759). The 3 samples, respectively, consisted of patients with chronic low back pain (n = 261), chronic back pain or hip/knee osteoarthritis pain (n = 240), and a history of stroke (n = 258). For each sample, anchor- and distribution-based approaches were used to estimate MIDs. Standard error of measurement and effect sizes were used as distribution-based MID estimates. Anchor-based MID estimates were established by mapping PROMIS pain interference scores onto established anchor measures, including the Brief Pain Inventory, and retrospective and prospective global ratings of change. The distribution- and anchor-based MID estimates showed convergence. For the pain samples, MID estimates ranged from 2 to 3 T-score points. For the nonpain sample, MID estimates ranged from 3.5 to 4.5 T-score points. The MID estimates were comparable across the 4 fixed-length scales. These MIDs can be used to evaluate treatment effects in research and clinical care and to calculate estimates for powering clinical trials.

Application of minimal important differences in degenerative knee disease outcomes: a systematic review and case study to inform BMJ Rapid Recommendations

ObjectivesTo identify the most credible anchor-based minimal important differences (MIDs) for patient important outcomes in patients with degenerative knee disease, and to inform BMJ Rapid Recommendations for arthroscopic surgery versus...

Patient-reported questionnaires in MS rehabilitation: responsiveness and minimal important difference of the multiple sclerosis questionnaire for physiotherapists (MSQPT)

BackgroundThe Multiple Sclerosis Questionnaire for Physical Therapists (MSQPT) is a patient-rated outcome questionnaire for evaluating the rehabilitation of persons with multiple sclerosis (MS). Responsiveness was evaluated, and minimal important difference (MID) estimates were calculated to provide thresholds for clinical change for four items, three sections and the total score of the MSQPT.MethodsThis multicentre study used a combined distribution- and anchor-based approach with multiple anchors and multiple rating of change questions. Responsiveness was evaluated using effect size, standardized response mean (SRM), modified SRM and relative efficiency. For distribution-based MID estimates, 0.2 and 0.33 standard deviations (SD), standard error of measurement (SEM) and minimal detectable change were used. Triangulation of anchor- and distribution-based MID estimates provided a range of MID values for each of the four items, the three sections and the total score of the MSQPT. The MID values were tested for their sensitivity and specificity for amelioration and deterioration for each of the four items, the three sections and the total score of the MSQPT. The MID values of each item and section and of the total score with the best sensitivity and specificity were selected as thresholds for clinical change.The outcome measures were the MSQPT, Hamburg Quality of Life Questionnaire for Multiple Sclerosis (HAQUAMS), rating of change questionnaires, Expanded Disability Status Scale, 6-metre timed walking test, Berg Balance Scale and 6-minute walking test.ResultsThe effect size ranged from 0.46 to 1.49. The SRM data showed comparable results. The modified SRM ranged from 0.00 to 0.60. Anchor-based MID estimates were very low and were comparable with SD- and SEM-based estimates. The MSQPT was more responsive than the HAQUAMS in detecting improvement but less responsive in finding deterioration. The best MID estimates of the items, sections and total score, expressed in percentage of their maximum score, were between 5.4% (activity) and 22% (item 10) change for improvement and between 5.7% (total score) and 22% (item 10) change for deterioration.ConclusionsThe MSQPT is a responsive questionnaire with an adequate MID that may be used as threshold for change during rehabilitation of MS patients.Trial registrationThis trial was retrospectively (01/24/2015) registered in ClinicalTrials.gov as NCT02346279.

Minimally Important Differences in Patient or Proxy-Reported Outcome Studies Relevant to Children: A Systematic Review.

No study has characterized and appraised all anchor-based minimally important differences (MIDs) associated with patient-reported outcome (PRO) instruments in pediatric studies. To complete a comprehensive systematic survey and appraisal of published anchor-based MIDs associated with PRO instruments used in children. Medline, Embase, and PsycINFO (1989 to February 11, 2015). Studies reporting empirical ascertainment of anchor-based MIDs among PROs used in pediatric care. All pertinent data items related to the characteristics of PRO instruments, anchors, and MIDs. Of 4179 unique citations, 30 studies (including 32 cohorts) proved eligible and reported on 28 unique PROs (8 generic, 13 disease-specific, 5 symptoms-specific, 2 function-specific), with 9 (32%) classified as patient-reported, 11 (39%) proxy-reported, and 8 (29%) both patient- and proxy-reported. Of the 30 studies, we rated 14 (44%) as providing highly credible estimates of the MID. Most cohorts (n = 20, 62%) recorded patients' direct response to the target PRO and the use of an independent standard of comparison (n = 25, 78%). Most, however, failed to effectively report measurement properties of the anchor (n = 24, 75%). We have not yet addressed the measurement properties of instrument to measure credibility; our search was restricted to 3 electronic sources, and we used a single data abstractor. Our study found 28 PROs that have been developed for children, with fewer than half providing credible estimates. Clinicians, clinical trialists, systematic reviewers, and guideline developers seeking to effectively summarize and interpret results of studies addressing PROs in child health are likely to find our comprehensive compendium of MIDs of use, both in providing best estimates of MIDs and identifying credible estimates.

Quality of Life in the Tube Versus Trabeculectomy Study

To report the vision-specific quality-of-life (QoL) outcomes in the Tube Versus Trabeculectomy (TVT) Study. Multicenter randomized clinical trial. Setting: Seventeen clinical centers. Patients 18-85 years of age with medically uncontrolled glaucoma who had previous cataract and/or glaucoma surgery. Tube shunt (350-mm2 Baerveldt glaucoma implant) or trabeculectomy with MMC. Vision-specific QoL using the NEI VFQ-25 and estimation of minimally important differences (MID) were the main outcome measures. Cross-sectional distribution- and anchor-based approaches were used to estimate MID. Clinical anchor measures included the mean deviation (MD) and logMAR visual acuity (VA) measurements. Clinically significant changes in anchor were defined as ≥2 dB MD and ≥0.2 logMAR. No significant differences in composite scores were observed between treatment groups, and no significant change in scores were seen over time. Mean (SD; range) values of clinical anchors at baseline were-16.6 (9.3;-32 to-0.5) dB for the surgical eye and 0.2 (0.3;-0.1 to 1.3) logMAR VA in the better-vision eye. For anchor-based cross-sectional analysis, composite score MID (95% CI) was 6.3 (4.6-7.9) for better-eye VA and 1.4 (0.9-1.9) for surgical eye MD. Distribution-based MID for the composite score was 6.0. Trabeculectomy and tube shunt surgery had similar impact on patient-reported vision-specific QoL measured using the NEI VFQ-25. In this cohort of patients with advanced glaucoma, MIDs varied depending on the clinical anchor used. Distribution-based MIDs corresponded well with anchor-based MIDs based on VA measures. The MID values reported here may be useful for others wishing to interpret NEI VFQ-25 scores in their advanced glaucoma patient cohort.

Minimally important difference of the Child Oral Health Impact Profile for children with orofacial anomalies.

BackgroundThe Child Oral Health Impact Profile (COHIP) is an instrument designed to measure the self-reported oral health-related quality of life of children between the ages of 8 and 15, including domains for oral health, functional well-being, social-emotional well-being, school environment and self-image. The purpose of this study was to estimate the minimally important difference (MID) of the COHIP for patients with cleft lip/palate.MethodsData from a 6-year, prospective, longitudinal cohort study of children with cleft lip/palate were analyzed to estimate the MID. Analysis was restricted to patients with data at baseline and first follow-up and not receiving a surgical intervention in the intervening years (N = 281). MIDs were estimated via the anchor-based method, using the Global Assessment of Change, and the effect size distribution method.ResultsBased on the distributional method, the minimally important differences were 0.16 (oral health), 0.12 (functional), 0.22 (social-emotional), 0.21 (school environment) and 0.19 (self-image). MID anchor estimates for COHIP domains ranged from −0.32 to 0.84. The anchor-based and effect size MID estimates for the overall COHIP score were 2.95 and 0.25, respectively.ConclusionThe minimally important difference of the Child Oral Health Impact Profile is recommended for interpreting clinically meaningful change in patients with cleft lip/palate.

Distribution-based estimates of minimal important difference for hospital anxiety and depression scale and impact of event scale-revised in survivors of acute respiratory failure.

This study will estimate distribution-based minimal important difference (MID) for the Hospital Anxiety and Depression Scale anxiety (HADS-A) and depression (HADS-D) subscales, and the Impact of Event Scale-Revised (IES-R) in survivors of acute respiratory failure (ARF). Secondary analyses of data from two US and three UK studies of ARF survivors (total N=1223). HADS-D and HADS-A were used to assess depression and anxiety symptoms. IES-R assessed post-traumatic stress disorder symptoms. Standard error of measurement, minimal detectable change90, 0.5 standard deviation (S.D.), and 0.2 S.D. were used to estimate MID for the combined sample, by studies, 6- and 12-month follow-ups, country and mental health condition. Overall, MID estimates converged to 2.0-2.5 for the HADS-A, 1.9-2.3 for the HADS-D and 0.17-0.18 for the IES-R. MID estimates were comparable across studies, follow-up, country and mental health condition. Among ARF survivors, 2.0-2.5 is a reasonable range for the MID for both HADS subscales, and 0.2 is reasonable for IES-R. Until anchor-based MIDs for these instruments are available, these distribution-based estimates can help researchers plan future studies and interpret the clinical importance of findings in ARF patient populations.

EQ-5D-derived health utilities and minimally important differences for chronic health conditions: 2011 Commonwealth Fund Survey of Sicker Adults in Canada.

The purpose of the study is to estimate the EQ-5D-derived health utilities associated with selected chronic conditions (hypertension, heart disease, arthritis, asthma or COPD, cancer, diabetes, chronic back pain, and anxiety or depression) and to estimate minimally important differences (MID) based on the Commonwealth Fund Survey of Sicker Adults in Canada. We used a cross-sectional survey of 3765 sick adults in Canada conducted in 2011 by the Commonwealth Fund. Health utilities were calculated for the entire sample and for each of the eight chronic health conditions. An ordinary least squares regression was used to estimate the utility decrement associated with these conditions with and without adjustment for socio-demographic factors. The MIDs were estimated using the anchor- and distribution-based methods. The adjusted utility decrement varied from 0.028 (95% confidence interval (CI) -0.049, -0.008) for diabetes to 0.124 (95% CI -0.142, -0.105) for anxiety or depression. The anchor-based MID for the entire group was 0.044 (95% CI 0.025, 0.062), and the distribution-based MID for the entire group was 0.091. The condition-specific MIDs using the distribution-based method ranged from 0.089 for cancer to 0.108 for asthma or COPD. The MID estimated by the distribution-based method was larger than the MID estimated by the anchor-based method, indicating that the choice of method matters. The impact of arthritis, anxiety or depression, and chronic back pain on health utility was substantial, all exceeding or approximating the MID estimated using either anchor- or distribution-based methods.

Minimally important difference estimates and methods: a protocol

IntroductionPatient-reported outcomes (PROs) are often the outcomes of greatest importance to patients. The minimally important difference (MID) provides a measure of the smallest change in the PRO that patients perceive...

Minimally important differences were estimated for six Patient-Reported Outcomes Measurement Information System-Cancer scales in advanced-stage cancer patients

Objective We combined anchor- and distribution-based methods to establish minimally important differences (MIDs) for six Patient-Reported Outcomes Measurement Information System (PROMIS)-Cancer scales in advanced-stage cancer patients. Study Design and Setting Participants completed 6 PROMIS-Cancer scales and 23 anchor measures at an initial ( n = 101) assessment and a follow-up ( n = 88) assessment 6–12 weeks later. Three a priori criteria were used to identify usable cross-sectional and longitudinal anchor-based MID estimates. The mean standard error of measurement was also computed for each scale. The focus of the analysis was on item response theory-based MIDs estimated on a T-score scale. Raw score MIDs were estimated for comparison purposes. Results Many cross-sectional (64%) and longitudinal (73%) T-score anchor-based MID estimates were excluded because they did not meet a priori criteria. The following are the recommended T-score MID ranges: 17-item Fatigue (2.5–4.5), 7-item Fatigue (3.0–5.0), 10-item Pain Interference (4.0–6.0), 10-item Physical Functioning (4.0–6.0), 9-item Emotional Distress-Anxiety (3.0–4.5), and 10-item Emotional Distress-Depression (3.0–4.5). Effect sizes corresponding to these MIDs averaged between 0.40 and 0.63. Conclusions This study is the first to address MIDs for PROMIS measures. Studies are currently being conducted to confirm these MIDs in other patient populations and to determine whether these MIDs vary by patients’ level of functioning.

The minimal important difference of exercise tests in severe COPD

Our aim was to determine the minimal important difference (MID) for 6-min walk distance (6MWD) and maximal cycle exercise capacity (MCEC) in patients with severe chronic obstructive pulmonary disease (COPD). 1,218 patients enrolled in the National Emphysema Treatment Trial completed exercise tests before and after 4-6 weeks of pre-trial rehabilitation, and 6 months after randomisation to surgery or medical care. The St George's Respiratory Questionnaire (domain and total scores) and University of California San Diego Shortness of Breath Questionnaire (total score) served as anchors for anchor-based MID estimates. In order to calculate distribution-based estimates, we used the standard error of measurement, Cohen's effect size and the empirical rule effect size. Anchor-based estimates for the 6MWD were 18.9 m (95% CI 18.1-20.1 m), 24.2 m (95% CI 23.4-25.4 m), 24.6 m (95% CI 23.4-25.7 m) and 26.4 m (95% CI 25.4-27.4 m), which were similar to distribution-based MID estimates of 25.7, 26.8 and 30.6 m. For MCEC, anchor-based estimates for the MID were 2.2 W (95% CI 2.0-2.4 W), 3.2 W (95% CI 3.0-3.4 W), 3.2 W (95% CI 3.0-3.4 W) and 3.3 W (95% CI 3.0-3.5 W), while distribution-based estimates were 5.3 and 5.5 W. We suggest a MID of 26 ± 2 m for 6MWD and 4 ± 1 W for MCEC for patients with severe COPD.

Estimating minimally important differences (MID) for the worst pain rating of the brief pain inventory (BPI)-short form (SF).

6112 Background: The BPI-SF is a widely used patient-reported outcome measure for assessing pain and has become the standard for use in clinical and research studies. The rating of worst pain is often selected as the primary outcome of interest; however, there are no published data available on its MID, particularly as a change score. The data presented in this analysis can help to enhance interpretation of the assessment. Methods: Patients with advanced breast cancer who enrolled in a randomized, double-blind, phase 3 study comparing denosumab vs. zoledronic acid in the treatment of bone metastases completed the BPI-SF, FACT-B, and EQ-5D questionnaires at baseline, week 5, and every 4 weeks thereafter until the end of the study. After assessing the correlation between change in the BPI worst pain rating with several potential anchors using the interval from baseline to week 25, we computed both anchor-based and distribution-based MID estimates for the BPI worst pain rating in both treatment arms combined...

Minimal Important Differences in the Migraine-Specific Quality of Life Questionnaire (MSQ) Version 2.1

To propose minimal important differences (MID) for the Migraine-Specific Quality of Life Questionnaire version 2.1 (MSQ v2.1). To our knowledge (to date), no published MID values exist for the MSQ v2.1 in any population. Analyses were performed on data from two pivotal clinical trials of topiramate for migraine prevention (n = 916), as well as from the QualityMetric National Headache Survey (n = 1016). Analyses included both distribution- and anchor-based MID techniques as well as group- and individual-level MID values. Group-level anchor-based MID values ranged from 3.2 [Role Restrictive domain (RR)] to 7.5 [Emotional Functioning domain (EF)], setting the minimum level of appropriate MID (which can also aid with power analysis). Individual-level distribution-based MID values resulted in highly similar estimates from two large databases: median MID of 8.5 for RR, 9.2 for Role Preventive (RP) and 12.0 for EF. Finally, individual-level anchor-based MID values ranged from 5.0 (RR and RP domains) to 10.6 (EF). For group-level purposes of calculating power for future studies, an MID of 3.2, 4.6 and 7.5 for RR, RP and EF is recommended. For within-group analyses for analysing clinical trial efficacy of each patient's change with responder analyses, 5 points is necessary for RR. For RP and EF, ranges are recommended: 5.0 to 7.9 for RP and 8.0 to 10.6 for EF. These latter two domains tend to have more error in the MID, and thus a sensitivity analysis with both ends of the range should be used to confirm significant differences in responder analyses.

The minimal detectable change cannot reliably replace the minimal important difference

Objective We compared the minimal important difference (MID) with the minimal detectable change (MDC) generated by distribution-based methods. Study Design Studies of two quality-of-life instruments (Chronic Respiratory Questionnaire [CRQ] and Rhinoconjunctivitis Quality of Life Questionnaire [RQLQ]) and two physician-rated disease-activity indices (Pediatric Ulcerative Colitis Activity Index [PUCAI] and Pediatric Crohn's Disease Activity Index [PCDAI]) provided longitudinal data. The MID values were calculated from global ratings of change (small change for CRQ and RQLQ; moderate for PUCAI and PCDAI) using receiver-operating characteristic (ROC) curve and mean change. Results were compared with five distribution-based strategies. Results Of the methods used to calculate the MDC, the 95% limits of agreement and the reliable change index yielded the largest estimates. In the patient-rated psychometric instruments, 0.5 SD was always greater than 1 standard error of measurements (SEM), and both fell between the mean change and the ROC estimates, on two of four occasions. The reliable change index came closest to MID of moderate change. Conclusion For patient-rated psychometric instruments, 0.5 SD and 1 SEM provide values closest to the anchor-based estimates of MID derived from small change, and the reliable change index for physician-rated clinimetric indices based on moderate change. Lack of consistency across measures suggests that distribution-based approaches should act only as temporary substitutes, pending availability of empirically established anchor-based MID values.

Minimal important differences of the SRS-22 Patient Questionnaire following surgical treatment of idiopathic scoliosis

The responsiveness of an instrument measuring health-related quality of life is an important indication of its construct validity. The SRS-22 Patient Questionnaire has become the most widely used patient-reported outcome instrument in the clinical evaluation of patients with idiopathic scoliosis. The responsiveness of the SRS-22 following surgical treatment in patients with idiopathic scoliosis has not been fully assessed. The aim of this study is to evaluate this factor by calculating the minimal important differences (MIDs) of the SRS-22 Questionnaire. The study included 91 patients with idiopathic scoliosis (77 females and 14 males), who underwent surgical treatment; mean age at the time of surgery was 18.1 years. Patients completed the SRS-22 questionnaire before surgery and at a follow-up visit (mean follow-up, 45.6 months). At follow-up, patients rated their overall situation as related to before surgery with a four-point Likert scale: 1-Worse, 2-Same, 3-Better, 4-Much Better. This evaluation represented the global perceived effect (GPE) and served as the anchor criterion for calculating the MID. MIDs were calculated using two approaches. The anchor-based MID (MID-A) was defined as the mean preoperative/follow-up difference in SRS-22 scores in the group of patients who stated they were much better than before surgery (GPE = 4). Using the same anchor criterion, the optimal cut-off value able to identify patients that had clearly improved was determined on a receiver operating characteristic (ROC) curve. In addition, the distribution-based MID (MID-D) was calculated by the standard error of measurement method. The MID-As found for the different subscales and the sum score were: pain 0.6, function 0.3, image 1.3, mental health 0.3, average sum score 0.6, and raw sum score 13.1. The cut-off values on the ROC curve were: pain 0.2, function 0.0, image 1.6, mental health 0.4, average sum score 0.4, and raw sum score 10. The MID-Ds were: pain 0.6, function 0.8, image 0.5, mental health 0.4, average sum score 0.5, and raw sum score 6.8. As was expected, the MID values differed according to the calculation method used. In light of the fact that the MID-As for the function and mental health subscales are below the measurement error of the instrument, it seems preferable to use the MID-D values for determining subscale changes. If the purpose is to analyze sum score changes (either the raw or average values), the MID-A is preferable because it includes the patient's evaluation of the results of surgery.

The responsiveness and validity of the CAMPHOR Utility Index

The aim of the present study was to validate and determine the minimal important difference (MID) and responsiveness of the Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR) Utility Index, a new tool enabling cost utility analyses. CAMPHOR, 6-min walking test (6MWT) and New York Heart Association (NYHA) data for 869 pulmonary hypertension patients (545 (63%) female; mean+/-SD age 56.6+/-15.4 yrs) from three centres were analysed. Utility was correlated with 6MWT data and calculated by NYHA class to assess validity. Effect sizes were calculated for those with two CAMPHOR assessments. Distribution and anchor-based MIDs were calculated. Analyses were carried out in patients receiving bosentan in order to determine whether or not those remaining in NYHA class III following treatment improved. The Utility Index distinguished between adjacent NYHA classes and correlated with 6MWT results. CAMPHOR subscales and utility were as responsive as the 6MWT (effect sizes ranged 0.31-0.69 for the CAMPHOR and 0.16-0.34 for the 6MWT). The within-group MID for the Utility Index was estimated to be approximately 0.09. Patients remaining in NYHA class III experienced, on average, a significant improvement (CAMPHOR Utility Index and functioning), which exceeded the MID. The CAMPHOR Utility Index is valid and responsive to change. Patients can experience significant and important improvements even if they do not improve on the basis of traditional outcomes, such as NYHA functional class.

Comparing and validating simple measures of patient-reported peripheral neuropathy (PRPN) for NCCTG Clinical Trials: A pooled analysis of 2,440 patients (pts)

9534 Background: The introduction of new anti-cancer therapies which cause pts to incur PN has required the development of new methods to assess this treatment outcome. This study compared and validated alternative methods of assessing PRPN in a series of North Central Cancer Treatment Group (NCCTG) clinical trials. Methods: Data were combined from 5 NCCTG trials (2440 pts) that used single- item questions scaled 0–100 relating to numbness and tingling respectively in fingers and toes to measure PN. Patient quality of life (QOL) was assessed using UNISCALE, Symptom Distress Scale (SDS), Profile of Mood States (POMS), Brief Pain Inventory (BPI) and Subject Global Impression of Change (SGIC). Associations between items were tested using Bland-Altman method and correlation. Wilcoxon tests compared QOL scores between pts with PN (score >40) vs. no PN. Change in PN and QOL was compared with a 20-point change defined as clinically meaningful. Minimal important differences (MID) were estimated using both anchor-based approach and distribution-based methods. Results: At baseline, the proportion of PRPN was 11% (numbness) and 10% (tingling); and 18% on each at last assessment. The correlation between PN items at baseline and last assessment was 0.8, with an average difference of <1 point on the 100-point scale. The MID estimate of SGIC in overall QOL, Physical Condition and Emotional State were 24, 21, 25 for numbness (respectively); and 19, 18, 17 for tingling (respectively). The distribution-based MID estimate was 12 for both PN items. Pts with substantial PN reported an average of 10 points lower QOL, mood and worse SDS and a 20 point-deficit in the BPI interference items. Pts with ≤20 points worsening in PN reported significant declines in SDS (p<0.001), worst pain (p<0.02), but not in POMS (p=0.64) or overall QOL (p=0.86). Conclusions: The two PN items for numbness and tingling were redundant. Anchor-based MID methods produced larger and inconsistent estimates relative to the distribution-based methods. Evidence of criterion validity and responsiveness indicates that these simple measures of PN can be used successfully in cancer clinical trials. No significant financial relationships to disclose.

A combination of distribution- and anchor-based approaches determined minimally important differences (MIDs) for four endpoints in a breast cancer scale

Objective To determine distribution- and anchor-based minimal important difference (MID) estimates for four scores from the Functional Assessment of Cancer Therapy–Breast (FACT-B): the breast cancer subscale (BCS), Trial Outcome Index (TOI), FACT-G (the general version), and FACT-B. Study design and setting We used data from a Phase III clinical trial in metastatic breast cancer (ECOG study 1193; n = 739) and a prospective observational study of pain in metastatic breast cancer ( n = 129). One third and one half of the standard deviation and 1 standard error of measurement were used as distribution-based criteria. Clinical indicators used to determine anchor-based differences included ECOG performance status, current pain, and response to treatment. Results FACT-B scores were responsive to performance status and pain anchors, but not to treatment response. By combining the results of distribution- and anchor-based methods, MID estimates were obtained: BCS = 2–3 points, TOI = 5–6 points, FACT-G = 5–6 points, and FACT-B = 7–8 points. Conclusion Distribution- and anchor-based estimates of the MID do show convergence. These estimates can be used in combination with other measures of efficacy to determine meaningful benefit and provide a basis for sample size estimation in clinical trials.