Journal Article Review

Transcription

1 Journal Article Review Janssen KW, van Mechelen W, Verhagen E. Bracing superior to neuromuscular training for the prevention of self-reported recurrent ankle sprains: a three-arm randomised controlled trial. Br. J Sports Med 2014;48: Last sentence of introduction: The aim of the current three-arm randomised controlled trial (RCT) was to evaluate the effectiveness of combined bracing and neuromuscular training, or bracing alone, against the use of neuromuscular training on recurrences of ankle sprain after usual care in athletes following an acute injury to the lateral ankle ligaments. 1. Study population: Athletes with an acute injury to the lateral ankle ligaments 2. Independent variables: Ankle bracing and neuromuscular training 3. Main outcome (dependent) variable: Recurrence of ankle sprain 4. Study design: Randomized controlled trial with three arms. 1. Does introduction make a logical case for the importance and relevance of the research question? Yes 2. Research question clearly identified? Yes 3. Able to identify study population, major independent variables, primary outcome variable, and study design? Yes METHODS 1. Subject population a. Inclusion criteria i. Sustained a lateral ankle sprain no more than 2 months prior to inclusion ii. Age between 18 and 70 years iii. Actively participating in sports for at least 1hr/wk. b. Exclusion criteria i. Insufficient mastery of the Dutch language ii. h/o vestibular problems iii. Suspected to have sustained a different injury than an ankle sprain after interview by telephone 2. Definition of variables a. Independent (interventions) i. Neuromuscular training: 8 week home-based neuromuscular training program consisting of 3 training sessions a week with maximum duration of 30 min/session. Exercises gradually increased in difficulty and load during the course of 8 weeks. Program had previously been linked to 35% reduction in ankle sprain recurrence risk. ii. Bracing: Semi-rigid ankle brace to be worn during all sports activities for the duration of the entire 12 months of follow-up. iii. Combination group: Underwent 8 week nm training program and wore brace for all sports activities during 8-wk training program only. b. Outcome variables (dependent variables) i. Primary: Incidence of ankle sprains based on a monthly questionnaire asking if they had suffered a recurrent sprain in the past month. ii. Secondary outcomes:

2 1. Severity of the recurrent sprains and costs related to the recurrent sprains. 2. Time-loss sprain: caused the participant to stop their sports activity and/or could not participate fully in the next planned sports activity. 3. Sprains leading to costs: Sprains that resulted in either self-care costs, the participant not being able to go to work or school, or required medical attention. c. Outline of study protocol (Figure 1) i. Participants recruited through non-medical channels (advertisements) ii. Study volunteers screened for inclusion and exclusion criteria iii. Eligible subjects completed baseline questionnaire and randomized to one of three intervention groups. Randomization stratified for care received (medical vs. non-medical) iv. Intervention 1. Neuromuscular training: 8-week home-based neuromuscular training program (three 30-minute sessions per week) that had been previously found to result in 35% reduction in ankle sprain recurrence risk. 2. Bracing group: Given semi-rigid ankle brace to be worn during all sports activities for 12 months. 3. Combination group: Received 8-week neuromuscular training program and given ankle brace to wear for sporting activities for 8 weeks. v. Subjects completed monthly on-line questionnaires regarding sports participation, use of preventive measures, and ankle sprains sustained during the preceding month, for 12 months. 1. External validity. Study population is a physically active group with mean age of 34. About 40% of subjects reported >3 ankle sprains within the past 5 years. Results may not be applicable to younger, more intense athletes, or more sedentary people of any age. 2. Primary outcome variable is clearly identified: Number of ankle sprains in the 12 months follow-up period. 3. Major outcome variable is the most clinically relevant patient oriented outcome given the study s question. 4. List potential confounders (examples) Age, education, gender, participation in sports with higher risk of ankle sprains, post-injury activity level, previous ankle injuries, severity of initial ankle sprains, previous rehabilitation and bracing/taping How were confounders dealt with in study design? All variables listed were assessed. Potential confounders were dealt with through randomization (baseline demographics and characteristics Table 1) and statistical adjustment to account for significant effect modification. Only severity of inclusion sprain was included in the results section, so I am assuming that the other variables listed did not significantly affect the results. 4. Study description does allow for clear understanding of the study protocol.

3 STATISTICS 1. Description of statistical analysis appears consistent with study design. Ankle sprain recurrence (the primary outcome) expressed as number of new recurrences per 1000 hours of sports participation. Comparisons between study groups done through Cox-regression survival analysis with the neuromuscular training group as the reference group. The influence of potential confounding variables was checked through regression analysis. 2. Power analysis done on cost differences in the interventions, not on a difference in ankle sprain recurrence between groups. 1. Primary outcome variable in power analysis (sample size calculation) was not the same primary outcome variable designated in the methods. 2. Power calculation is based on cost-effectiveness aspect of the study, which is not reported. This discrepancy could increase the chance of a type II error (conclude that there is no difference between groups when there really is) due to too few subjects in each group. RESULTS 1. First table compares baseline characteristics of groups. Text states that groups were comparable to all other measured variables at baseline although statistical comparison is not presented. The exception is the percentage medically treated was greater in the training and combi groups compared to the brace group. In reviewing the table, it looks like the brace group had proportionally more grade one injuries than the other groups, and therefore were as a group less severely injured, but this apparently did not reach statistical significance. 2. Figure 1 accounts for all subjects who initially entered the study. Drop-out rates were not significantly different between the groups. 3. Primary outcome measure: Number of ankle sprains during the 12-month follow-up. The basic data is presented in text: 29 (27%) in the training group, 17 (15%) in the brace group and 23 (19%) in the combi group suffered a recurrent ankle sprain during the 12-month follow-up. Statistics on these differences are not presented. Instead, the authors express the incidence of recurrent ankle sprain per 1000 hours of sport participation. Training group 2.51 ankle sprains per 1000h of sports, 1.34 in brace group, and 1.78 in the combi group. 4. How were confounders dealt with? a. Cox-regression analysis adjusting for severity of inclusion sprain found that risk of recurrent ankle sprain was lower for the brace group compared to training group (RR 0.53, 95% CI 0.28 to 0.95). RR was also lower in combi group compared to training group (RR 0.71, 95% CI 0.41 to 1.22) but this was not statistically significant. A comparison of the Brace vs. the Combi group was not presented, but were probably not statistically different based on the raw data. For some reason the numbers quoted in the text are slightly different than the numbers listed in the first row of Table Sub-group analysis is presented in Table 2

4 1. Internal validity: Are the major potential confounders dealt with adequately? Major confounders appear to be appropriately assessed and accounted for. 2. Are all subjects who initially entered the study accounted for? Yes see Figure 1 3. Intent-to-treat analysis? Yes. Of interest, compliance to the treatment protocols in all groups was poor full compliance rates were 45% in training group, 23% in brace group, and 28% in combi group (remember that the brace group compliance was over 12 months, while the training group meet for only 2 months). There was also intervention cross-over 15% of subjects in the training group wore a brace during the first 2 months, and 15% of in the brace group consistently performed neuromuscular training during the first 2 months. 4. Emphasis on primary outcome (i.e., recurrent ankle sprains)? Yes 5. Are the results clinically important? Results are presented in 3 different ways: - Percentage of subjects in each group who suffered a recurrent ankle sprain in the follow-up period - The incidence of recurrent ankle sprain per 1000 hours of sport participation - Relative risk of suffering a recurrent ankle sprain through Cox-regression analysis. Simple calculations of Absolute Risk Reduction (ARR), Relative Risk Reduction (RRR), and Number Needed to Treat (NNT) can be easily done based on the percentage of subjects within each group who suffered a recurrent ankle sprain during the follow-up period. In this study, the neuromuscular training group was considered the control group. Control (training) event rate (CER):.27 Experimental (brace) event rate (EER):.15 Experimental (Combi) event rate (EER):.19 Brace Group as experimental group: Absolute Risk Reduction (ARR) =.12 Relative Risk Reduction =.12/.27 =.44 Number Needed to Treat (NNT) = 1/.12 = 8.3 Combi Group as experimental group : ARR =.08 RRR =.30 NNT = 12.5 If we consider the Combi group as the control group and the brace group as the experimental group: ARR =.04 RRR =.21 NNT = 25 In words, in this study, the protocol of bracing for sporting activities for 12 months reduced the rate of recurrent ankle sprains by 12% compared to 2 months of neuromuscular training. 8 people needed to be braced for 12 months to prevent 1 person from having a recurrent ankle sprain.

5 Important Point: Calculations of ARR, RRR, and NNT are not measures of statistical significance. They do not account for the size of the sample or the size of the standard error of the mean. They are most appropriately calculated on data that has already been shown to be statistically significant. Discussion (my discussion, not the author s) Study design appears appropriate for research question. Internal validity good potentially confounding variables accounted for as best as can be expected given the real world clinical study design. Appropriate intent -to-treat analysis with focus on primary outcome variable (incidence of recurrent ankle sprains. Poor compliance with research protocols should decrease differences between groups, so does not weaken the findings. Clinical significance/applicability : Whether it is worth having 8 patients wear a brace for 12 months to prevent one person getting a recurrent ankle sprain is a value judgment for the patient and clinician to decide, but is certainly within the range of other therapeutic interventions External validity limited - results may not be applicable to younger, more intense athletes, or more sedentary people of any age. My biggest issue with the study is that the finding that recurrent ankle sprains are reduced if a patient wears a rigid brace for 12 months is (to my mind) self-evident. The study did not answer the question if ankle bracing affects performance an important consideration for competitive athletes. I would also be interested to see if ankle sprains increased after the subjects stopped wearing the brace (after a year) or if they have to wear the brace indefinitely to prevent sprains.