Reporting of minimum clinically important differences in surgical trials

Abstract

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.

The Minimal Clinically Important Difference After Simple Decompression for Ulnar Neuropathy at the Elbow

“…First, MCID helps to estimate the required sample size so that a study has sufficient power to detect the true differences and therefore assess treatments better. (17,18) It is encouraging that there is an increase in the number of surgical trials including sample size estimates in the manuscripts over the last 3 decades; however, a study conducted by Kashani et al revealed that only 21% of the surgical trials considered MCID in their sample size calculations. (17) For to be adequately powered and not report negative results, appropriate MCID values should be considered in the sample size estimation at the beginning of trials.…”

Outcomes reported in high-impact surgical journals

“…As has been noted, ‘a numerical score of a function or symptom is sometimes difficult to interpret and it gives the clinician little information as to the actual severity of symptoms being experienced by the patient’. The area in which a quantitative understanding of PROs is needed most is comparative effectiveness research, where studies may often be underpowered to detect the changes they wish to detect, in part because of inconsistent use and reporting of PRO measures.…”

How to dissect surgical journals: IX – Sample size

“…Kashani et al 5 . found that only 21% (100/486) of admissible surgical trials mentioned a value for the minimum clinically important difference when estimating the sample size.…”