Fragility index of urological literature regarding medical expulsive treatment

A fragility index analysis of clinical trials evaluating low-intensity extracorporeal shockwave therapy for erectile dysfunction

Erectile dysfunction is a common sexual dysfunction that affects a significant proportion of men. Low-intensity extracorporeal shockwave therapy has been evaluated in multiple clinical trials as a therapeutic option for men with erectile dysfunction. The robustness of these clinical trials is not well defined, as the trials are hindered by inconsistent treatment protocols, small study arm size and short follow-up intervals. The fragility index is a statistical analysis which is used to evaluate the robustness of clinical trials. It is calculated by evaluating the minimum number of patients in a given trial arm that would be required to have an alternative outcome to alter the statistical significance of the results. The lowest fragility index in statistically significant trials is 1, meaning that if just one participant experienced an alternate outcome, the results would no longer achieve statistical significance. The upper limit is determined by the number of participants in a given arm of the trial. Herein, a scoping review of clinical trials evaluating the efficacy of low-intensity extracorporeal shockwave therapy in erectile dysfunction to determine the fragility index of trials with clinically significant results. We hypothesized that the fragility index would be low, indicating the results are less robust and generalizable.

Fragility of overactive bladder medication clinical trials: A systematic review

PURPOSE

Overactive bladder (OAB) syndrome significantly impairs quality of life, often necessitating pharmacological interventions with associated risks. The fragility of OAB trial outcomes, as measured by the fragility index (FI: smallest number of event changes to reverse statistical significance) and quotient (FQ: FI divided by total sample size expressed as a percentage), is critical yet unstudied.

MATERIALS AND METHODS

We conducted a systematic search for randomized controlled trials on OAB medications published between January 2000 and August 2023. Inclusion criteria were trials with two parallel arms reporting binary outcomes related to OAB medications. We extracted trial details, outcomes, and statistical tests employed. We calculated FI and FQ, analyzing associations with trial characteristics through linear regression.

RESULTS

We included 57 trials with a median sample size of 211 participants and a 12% median lost to follow-up. Most studies investigated anticholinergics (37/57, 65%). The median FI/FQ was 5/3.5%. Larger trials were less fragile (median FI 8; FQ 1.0%) compared to medium (FI: 4; FQ 2.5%) and small trials (FI: 4; FQ 8.3%). Double-blinded studies exhibited higher FQs (median 2.9%) than unblinded trials (6.7%). Primary and secondary outcomes had higher FIs (median 5 and 6, respectively) than adverse events (FI: 4). Each increase in 10 participants was associated with a +0.19 increase in FI (p < 0.001).

CONCLUSIONS

A change in outcome for a median of five participants, or 3.5% of the total sample size, could reverse the direction of statistical significance in OAB trials. Studies with larger sample sizes and efficacy outcomes from blinded trials were less fragile.

What's in a P-Value? A Fragility Analysis of RCTs in the AUA Guidelines for Benign Prostatic Hyperplasia

OBJECTIVE

To use the fragility index (FI) and fragility quotient (FQ) to assess the strength of statistically significant findings for randomized controlled trials (RCTs) cited in the American Urological Association (AUA) guidelines for benign prostatic hyperplasia.

METHODS

Two investigators independently screened the AUA guidelines for management of benign prostatic hyperplasia for RCTs cited as evidence for recommendations. Investigators extracted data related to event rate per group and loss to follow-up which was compared against the FI. Stata 17.0 was used to calculate the FI and FQ which was then summarized and reported according to primary or secondary endpoints.

RESULTS

Among the 373 citations in the AUA guidelines, 24 RCTs met inclusion criteria with 29 distinct outcomes analyzed. The median fragility index was 12 (IQR = 4-38), indicating that twelve alternative events to either study arm would nullify statistical significance. Six studies had a FI of ≤2, indicating that only 1-2 outcomes would need to be changed in order to render nonsignificance of results. In 10/24 RCTs, the number of patients lost to follow-up was greater than the FI.

CONCLUSION

The AUA Clinical Practice Guidelines for management of benign prostatic hyperplasia cite RCTs with more robust findings when compared to previous studies assessing fragility in the field of Urology. While several included studies had high fragility, the median FI in our analysis was approximately 4-5 times higher than comparable studies of urologic RCTs. However, there are areas where improvement is necessary to support the highest quality of evidence-based medicine.

The Fragility Index of Randomized Controlled Trials for Preterm Neonates

BACKGROUND

As a metric to determine the robustness of trial results, the fragility index (FI) is the number indicating how many patients would be required to reverse the significant results. This study aimed to calculate the FI in randomized controlled trials (RCTs) involving premature.

METHODS

Trials were included if they had a 1:1 study design, reported statistically significant dichotomous outcomes, and had an explicitly stated sample size or power calculation. The FI was calculated for binary outcomes using Fisher's exact test, and the FIs of subgroups were compared. Spearman's correlation was applied to determine correlations between the FI and study characteristics.

RESULTS

Finally, 66 RCTs were included in the analyses. The median FI for these trials was 3.00 (interquartile range [IQR]: 1.00-5.00), with a median fragility quotient of 0.014 (IQR: 0.008-0.028). FI was ≤ 3 in 42 of these 66 RCTs (63.6%), and in 42.4% (28/66) of the studies, the number of patients lost to follow-up was greater than that of the FI. Significant differences were found in the FI among journals (p = 0.011). We observed that FI was associated with the sample size, total number of events, and reported p-values (r _s = 0.437, 0.495, and -0.857, respectively; all p < 0.001).

CONCLUSION

For RCTs in the premature population, a median of only three events was needed to change from a "non-event" to "event" to render a significant result non-significant, indicating that the significance may hinge on a small number of events.