Reporting of minimum clinically important differences in surgical trials

Background: The minimum clinically important difference (MCID) is the smallest difference in outcome between the groups that would be of clinical interest. It influences the estimates that are made to determine the required sample side. The aim of this study was to explore the reporting of the MCID in surgical trials. Method: Surgical trials that were published between January 1981 and December 2006 in five prestigious surgical journals were evaluated. Selected for study were trials that studied two groups and reported the main outcome event as a proportion. Results: Only 21% (100/486) of the admissible surgical trials mentioned a value for the MCID when estimating the sample size. There was a trend, however, for compliance with these factors to increase during the study period. The present post‐hoc calculations of the required sample size, which were based on the observed differences between the groups at the end of the study, suggested that one‐third of the trials should have accrued at least fivefold the number of patients. Although reporting an estimate of the sample size was associated with the study of more patients (median sample size 145 vs 100), it was not associated with the reporting of more positive results, that is, 61% (95/155) versus 65% (214/331). Conclusion: There has been an improvement in the proportion of surgical trials reporting formal estimates of sample size during the last three decades. But the construct of these estimates is often suspect because of a failure to provide realistic values for the MCID.     

Testing minimal clinically important difference: consensus or conundrum?

Background ContextVarious methodologies have been used in attempting to elucidate a standard method for calculating minimal clinically important difference (MCID). A consensus-based decision (Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials [IMMPACT] group) suggested a 30% reduction from baseline as a means to define the MCID of self-report back pain measures. Additionally, important psychometric issues need to be addressed regarding use of an independent measure of the same construct as an external criterion, instead of simply using another self-report measure, when using an anchor-based approach to MCID.PurposeThe purpose was to test the validity of recently published guidelines regarding MCID using self-report back pain measures and objective socioeconomic outcomes.Study Design/SettingThis is a prospective study assessing change scores on commonly used spinal pain assessment measures in patients with chronic disabling occupational spinal disorders (CDOSDs) treated in a regional referral rehabilitation center performing interdisciplinary functional restoration.Patient SampleThe study consisted of consecutive cohort of patients (N=1,180) with CDOSDs completing a functional restoration program.Outcomes MeasuresSelf-report measures including the Oswestry Disability Index (ODI) and the physical component summary (PCS) and mental component summary (MCS) of the Short Form-36 (SF-36) obtained before and after treatment, were compared with objective socioeconomically relevant outcomes obtained 1 year after treatment (ie, work status and additional health-care utilization), that were the external criteria for evaluating MCID.MethodsPre- to posttreatment improvement was calculated separately for each measure, and subjects were divided into two groups based on the change in scores relative to baseline: 30% or greater versus less than 30% improvement. One-year posttreatment objective socioeconomic outcomes were used as independent external criteria relevant to the CDOSD population. This population is often studied as the most costly and problematic cohort in spine care.ResultsThe ODI and SF-36 MCS were not associated with any of the objective 1-year outcomes used as external criteria. Reduced post-rehabilitation health-care utilization (based on the percentage of patients pursuing health care from a new provider) was weakly associated with 30% or greater improvement on the SF-36 PCS, relative to patients whose scores changed by less than 30% relative to baseline (17.0% vs. 21.1%). The same was true for the ODI and return-to-work.ConclusionsWhen objective and independent criteria are used (socioeconomic outcomes) in a CDOSD cohort, the 30% improvement in the ODI and SF-36 may not be a valid MCID index. This replicates similar conclusions made by an independent research group using a distribution-based approach to MCID. The validity of the MCID concept rests on future research using objective external criteria. Moreover, there remains a question whether the term “important” in MCID can be unequivocally and operationally defined as a reliable construct.     

Usefulness of minimum clinically important difference for assessing patients with subaxial degenerative cervical spine disease: statistical versus substantial clinical benefit

Background

The measurement of the therapeutic outcome of cervical spine surgeries commonly relies on four main patient reported outcomes (PROs): Neck Disability Index (NDI), Visual Analog Scale (VAS) for pain, and Short Form-36 (SF-36) Physical (PCS) and Mental (MCS) Component Summary. However, the clinical impact of such scores and how they could effectively measure therapeutic efficacy remains unclear. In this context, the concept of minimum clinically important difference (MCID) is developing into the standard by which to evaluate treatments, patient satisfaction and cost-effectiveness.

Methods

Eighty-eight consecutive patients undergoing surgery for subaxial degenerative cervical spine disease were selected from a prospective blinded database. PROs (NDI, PCS, MCS and VAS) were collected preoperatively, and together with blinded Surgeon Ratings (SR) at 3 months and 6 months post-surgery. Four anchor-based approaches were used to calculate different MCIDs. Three anchors (VAS, HTI (Health Transition Item of the SF-36) and SR) were used to evaluate surgery outcome. The best clinically and statistically relevant MCID was chosen.

Results

On average, all patients presented with a statistically significant improvement (p?<?0.001) postoperatively for NDI (27.42 to 19.42), PCS (33.02 to 42.03), MCS (44 to 50.74) and VAS (2.85 to 1.93). The four MCID anchor-based approaches yielded a range of values for each PRO: 2.23–16.59 for PCS, 0.11–16.27 for MCS and 2.72–12.08 for NDI. When compared to the VAS and HTI anchors, the area under the ROC curve was greater for SR. This finding suggests that SR may be a more reliable anchor for MCID calculation.

Conclusion

The MDC (minimum detectable change) approach together with the SR anchor appears to be the most appropriate MCID method. It offers the greatest area under the ROC curve (threshold above the 95 % CI), and the choice of the anchor did not significantly affect this result. MCID values for this dataset were 5.6 for PCS, 5.12 for MCS and 2.41 for NDI.     

Preoperative patient activation predicts minimum clinically important difference for PROMIS pain and physical function in patients undergoing elective spine surgery

BACKGROUND CONTEXTPatient activation is a patient's willingness to take independent actions to manage their own health care.PURPOSEThe goal of this study is to determine whether preoperative patient activation measure (PAM) predicts minimum clinically important difference (MCID) for Patient-Reported Outcomes Measurement Information System (PROMIS) pain, physical function, depression, and anxiety for patients undergoing elective spine surgery.STUDY DESIGN/SETTINGRetrospective review.PATIENT SAMPLEA single-institution, academic database of patients undergoing elective spine surgery.OUTCOME MEASUREMCID at 1-year follow-up for PROMIS pain, physical function, depression and anxiety.METHODSWe retrospectively reviewed a single-institution, academic database of patients undergoing elective spine surgery. Preoperative patient activation was evaluated using the PAM-13 survey, which was used to stratify patients into four activation stages. Primary outcome variable was achieving MCID at 1-year follow-up for PROMIS pain and physical function. Multivariable logistic regression analysis was used to determine impact of patient activation on PROMIS pain and the physical function.RESULTSOf the 430 patients, 220 (51%) were female with a mean age of 58.2±16.8. Preoperatively, 34 (8%) were in activation stage 1, 45 (10%) in stage 2, 98 (23%) in stage 3, and 253 (59%) in stage 4. At 1-year follow up, 248 (58%) achieved MCID for PROMIS physical function, 256 (60%) achieved MCID for PROMIS pain, 151 (35.28%) achieved MCID for PROMIS depression, and 197 (46%) achieved MCID for PROMIS anxiety. For PROMIS physical function, when compared to patients at stage 1 activation, patients at stage 2 (aOR:3.49, 95% CI:1.27, 9.59), stage 3 (aOR:3.54, 95% CI:1.40, 8.98) and stage 4 (aOR:7.88, 95% CI:3.29, 18.9) were more likely to achieve MCID. For PROMIS pain, when compared against patients at stage 1, patients at stage 3 (aOR:2.82, 95% CI:1.18, 6.76) and stage 4 (aOR:5.44, 95% CI:2.41, 12.3) were more likely to achieve MCID. For PROMIS depression, when compared against patients at stage 1, patients at stage 4 were more likely to achieve MCID (Adjusted Odds Ratio (aOR):2.59, 95% CI:1.08–6.19). For PROMIS anxiety, when compared against patients at stage 1, stage 3 (Adjusted Odds Ratio (aOR):3.21, 95% CI:1.20–8.57), and stage 4 (aOR:5.56, 95% CI:2.20–14.01) were more likely to achieve MCID.CONCLUSIONPatients at higher stages of activation were more likely to achieve MCID for PROMIS pain, physical function, depression, and anxiety at 1-year follow-up. Routine preoperative assessment of patient activation may help identify patients at risk of poor outcomes.     

The minimum clinically important difference for the Japanese version of the new Knee Society Score (2011KSS) after total knee arthroplasty

BackgroundThe new Knee Society Score (2011KSS) has been used to evaluate post-operative outcomes after total knee arthroplasty (TKA). However, there is no minimum clinically important difference (MCID) for 2011KSS. The purpose of this study is to define MCID of 2011KSS after TKA.MethodsPatients who underwent primary TKA for primary knee osteoarthritis between April 2012 and December 2016 were included in the study. The Japanese version of 2011KSS and original Knee Society Score (OKSS) were recorded preoperatively and at one-year postoperatively. With improvement in pain score of OKSS as an anchor, an anchor-based approach was used to identify the MCID of 2011KSS. The improvement in pain of OKSS was classified into 5 categories. The MCID was determined using a linear regression analysis of delta 2011KSS against improvement in the category of pain in OKSS. The MCID for 2011KSS expectation was not calculated because the items of pre- and post-operative questionnaires were different.ResultsFive hundred and twenty-two cases were enrolled (age: 74.8 ± 7.3 years, female: 80.0%). After 1-year follow-up, 344 TKAs were finally included (age: 74.6 ± 7.1 years, female: 77.9%). Linear regression analyses showed that MCID for 2011KSS was 1.9 (95% confidential interval (CI): 1.3–2.5) in symptom, 2.2 (95%CI: 1.4–2.9) in satisfaction, and 4.1 (95%CI: 2.5–5.7) in functional activities.ConclusionsMCID for 2011KSS was successfully calculated. These MCID values make the 2011KSS a more efficient tool for evaluating the physical activities of the populations of patients undergoing TKA. These MCID values can also be used to calculate sample size to evaluate the power of a study in designing clinical studies.     

The minimal clinically important difference in the Gastrointestinal Quality-of-Life Index after cholecystectomy

Background  

The minimal clinically important difference (MCID) for the Gastrointestinal Quality of Life Index (GIQLI) is unknown, which limits its application and interpretation. This study aimed to estimate MCIDs for the GIQLI scores of patients after they had undergone cholecystectomy.     

The minimal clinically important difference of the Carpal Tunnel Syndrome Symptom Severity Scale

PURPOSE: To identify the change score in the Symptom Severity Scale (SSS) of the Carpal Tunnel Syndrome (CTS) Questionnaire that is associated with an important change in clinical status. METHODS: Twenty-eight patients with CTS treated with a carpal tunnel steroid injection completed the Brigham and Women's Hospital CTS Questionnaire before steroid injections and at the 3-week follow-up visit. Satisfaction was determined by postcare review of the clinical management. To calculate the minimal clinically important difference, receiver operating characteristic curves were created. The area under the curve was calculated to determine and compare the responsiveness of the entire SSS and the pain and sensory questions in isolation. RESULTS: The SSS of the CTS Questionnaire, including its pain and sensory domain, can show a meaningful clinical improvement after carpal tunnel injection. The SSS, its sensory domain, and its pain domain were statistically better than chance. All 3 measures showed predictive ability; however, the total SSS was the most sensitive in detecting a change. The minimal clinically important difference in the score of the SSS after carpal tunnel steroid injection was found to be 1.04. CONCLUSIONS: The SSS can be used to distinguish a clinically important change after carpal tunnel injection. A decrease of 1.04 or more in the SSS score may indicate a clinically important change in a patient's state of health. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic, Level I.     

The association of comorbidity indices and minimal clinically important difference in a population undergoing shoulder arthroplasty

BackgroundShoulder arthroplasty (SA) procedures are increasingly common. The Charlson and Elixhauser indices are ICD-10 based measures used in large databases to describe the patient case mix in terms of secondary medical conditions. There is a paucity of data on the relationship between these indices and patient-reported outcome measures (PROMs) after shoulder arthroplasty.MethodsPatients undergoing SA from 2016-2018 were identified in the electronic medical records. Charlson and Elixhauser comorbidities were used to calculate comorbidity scores according to established algorithms (eg Elixhauser-Walraven). Patient shoulder-specific (American Shoulder and Elbow Surgeons (ASES) score and Shoulder Activity Scale (SAS)) and general health scales (SF-12 Mental Component Score (MCS) and Physical Component Score (PCS) and Patient-Reported Outcomes Measurement Information System-Pain Interference (PROMIS-PI)) PROMs were obtained from our institution’s shoulder registry. Linear regression models adjusting for age and sex evaluated associations between comorbidity scores and PROMs. Receiver operating characteristic (ROC) curves determined optimal cutoffs, maximizing sensitivity and specificity to identify patients likely to fail to meet minimal clinically important difference (MCID) values.ResultsA total of 1817 SA procedures were identified. Higher Charlson and Elixhauser-Walraven scores were significantly associated with lower baseline SAS and SF-12 PCS. Patients with higher Charlson scores had lower baseline ASES (P = .003) and lower baseline (P = .0002) and 2-year (P = .02) SF-12 MCS. No significant associations were found for PROMIS-PI with either index. The Charlson score better predicted the failure to meet MCID for SF-12 PCS with an AUC of 0.64, compared to 0.55 for Elixhauser-Walraven. Conversely, Elixhauser-Walraven better predicted PROMIS-PI with an AUC of 0.66, compared to 0.53 for Charlson. Moderate AUCs were observed for the remaining PROMs, ranging from 0.57-0.64, with little difference between index scores.ConclusionHigher Charlson and Elixhauser-Walraven scores were associated with lower baseline scores on most PROMs. Generally, the Charlson score performed better than the Elixhauser-Walraven score in predicting worse outcomes at 2 years. Comorbidity indices may be useful as a decision aid to provide appropriate expectations of outcomes for patients undergoing SA.     

Determination of minimum clinically important difference (MCID) in pain,disability, and quality of life after revision fusion for symptomatic pseudoarthrosis

Background contextSpinal surgical outcome studies rely on patient reported outcome (PRO) measurements to assess the effect of treatment. A shortcoming of these questionnaires is that the extent of improvement in their numerical scores lacks a direct clinical meaning. As a result, the concept of minimum clinically important difference (MCID) has been used to measure the critical threshold needed to achieve clinically relevant treatment effectiveness. Post hoc anchor-based MCID methods have not been applied to the surgical treatment for pseudoarthrosis.PurposeTo determine the most appropriate MCID values for visual analog scale (VAS), Oswestry Disability Index (ODI), Short Form (SF)-12 physical component score (PCS), and European Quality of Life 5-Dimensions (EQ-5D) in patients undergoing revision lumbar arthrodesis for symptomatic pseudoarthrosis.Study design/ settingRetrospective cohort study.MethodsIn 47 patients undergoing revision fusion for pseudoarthrosis-associated back pain, PRO measures of back pain (BP-VAS), ODI, physical quality of life (SF-12 PCS), and general health utility (EQ-5D) were assessed preoperatively and 2 years postoperatively. Four subjective post hoc anchor-based MCID calculation methods were used to calculate MCID (average change; minimum detectable change; change difference; and receiver operating characteristic curve analysis) for two separate anchors (health transition index (HTI) of SF-36 and satisfaction index).ResultsAll patients were available for a 2-year PRO assessment. Two years after surgery, a significant improvement was observed for all PROs; Mean change score: BP-VAS (2.3±2.6; p<.001), ODI (8.6%±13.2%; p<.001), SF-12 PCS (4.0±6.1; p=.01), and EQ-5D (0.18±0.19; p<.001). The four MCID calculation methods generated a wide range of MCID values for each of the PROs (BP-VAS: 2.0–3.2; ODI: 4.0%–16.6%; SF-12 PCS: 3.2–6.1; and EQ-5D: 0.14–0.24). There was no difference in response between anchors for any patient, suggesting that HTI and satisfaction anchors are equivalent in this patient population. The wide variations in calculated MCID values between methods precluded any ability to reliably determine what the true value is for meaningful change in this disease state.ConclusionsUsing subjective post hoc anchor-based methods of MCID calculation, MCID after revision fusion for pseudoarthrosis varies by as much as 400% per PRO based on the calculation technique. MCID was suggested to be as low as 2 points for ODI and 3 points for SF-12. These wide variations and low values of MCID question the face validity of such calculation techniques, especially when applied to heterogeneous disease and patient groups with a multitude of psychosocial confounders such as failed back syndromes. The variability of MCID thresholds observed in our study of patients undergoing revision lumbar fusion for pseudoarthrosis raises further questions to whether ante hoc or Delphi methods may be a more valid and consistent technique to define clinically meaningful, patient-centered changes in PRO measurements.     

The minimum important difference for the Pelvic Organ Prolapse-Urinary Incontinence Sexual Function Questionnaire

Introduction and hypothesis

Although the Pelvic Organ Prolapse-Urinary Incontinence Sexual Function Questionnaire (PISQ) is widely used to assess sexual function in women, the minimum important difference (MID) (defined as the smallest difference in scores of a patient-reported outcome measure that is perceived by patients as beneficial or harmful and which would lead the clinician to consider a change in treatment) is not known. The objective was to estimate the MID for the PISQ.

Methods

Two study populations, one of women with overactive bladder (OAB) and urgency UI (UUI) treated with tolterodine in a placebo-controlled trial (cohort I), and one of women treated surgically for prolapse and/or UI (cohort II) were used. Cohort I anchors were the Overactive Bladder Questionnaire (OAB-q), the Patient Perception of Bladder Condition (PPBC), the Patient Perception of Treatment Benefit Questionnaire (PPTBQ), and the change in number of UUI episodes in bladder diaries. Distribution MIDs were also calculated.

Results

In the anchor-based analysis, the MID values for changes in PISQ total scores at 3 months in cohort I were 5 points using the UUI anchor (diary-dry women), 5 points using the PPBC anchor, 5 points with the PPTBQ, and 9 points with the OAB-q. In cohort II, the MID at week 12 in PISQ total scores was 7 points in women with improved IIQ-7 scores. The distribution-based MID in PISQ total scores was 5.3 points in cohort I and 5.8 points in cohort II.

Conclusion

A reasonable estimate of MID for the PISQ total score is 6 points. Improvements that meet these thresholds may be considered clinically important.