Conservative treatment or surgery for shoulder impingement: updated meta-analysis

Since the early 1990s, none of the randomized controlled trials (RCTs) conducted on a surgical approach in the treatment of shoulder impingement found evidence on the superiority of surgery when compared to non-operative treatment. Controversial opinions on the subject have still been appearing [1–3]. Our meta-analysis on the topic published in 2015 stated that surgery is not more effective than conservative treatment in shoulder impingement [4]. The updated search was conducted from January 2014 until the end of April 2019 at the same databases: Medline, Embase, Cinahl, Central, and Science Citation Index. The search has now resulted in a few additional RCTs on the topic published recently. Employing the criteria described in our previous publication, two RCTs were added to a meta-analysis [5,6]. While Ketola et al. have also recently published the updated report [7], their results were included here as stated in 2009 due to a substantial drop-out rate of 33% after a longer follow-up. The study by Peters et al. [8], considered previously having a high risk of systematic bias, was excluded from the present meta-analysis as there was a great uncertainty concerning the variance of the results reported. In this meta-analysis, change in pain severity level was used when possible. Otherwise, another available main outcome was used, particularly, Neer and Oxford shoulder scores. The pooled result was calculated as a standardized mean difference between the groups along with its 95 confidence interval (95% CI) (Figure 1). Random effects approach was used. All eight included RCTs demonstrated insignificant effect sizes. The pooled effect was 0.12 (95% CI 0.0 to 0.25) indicating small and statistically insignificant difference between results of surgery and conservative treatment. The heterogeneity was insignificant with I 0.0%. There were no indications of publication bias with insignificant Egger’s regression intercept 1.8 (95% CI 0.6 to 4.3) and no need for a trim-and-fill correction. The analysis was made using comprehensive meta-analysis (CMA), Version 3.3, available from www. meta-analysis.com. Both newly added RCTs were apprized as studies with low risk of systematic bias (Table 1). Overall, of eight included studies, six were considered to be of low risk of systematic bias. The metaanalysis involved data obtained from 842 patients with shoulder impingement – 418 treated surgically and 424 received conservative treatment including different sorts of physiotherapy. The follow-ups varied from 0.5 up to 8 years. The average age of patients varied from 42 up to 54 years. In the meta-analysis, pain severity figures were available for six RCTs [5,6,9–14]. The results strengthened the conclusions of our previous review indicating that there is evidence on the equal effectiveness of surgical and conservative treatment of shoulder impingement. The results point at the high-quality level of evidence (grade A according to EBM grading system – “several high-quality studies with consistent results”) and further research is very unlikely to change the present confidence in the estimate of effect. These results support conservative treatment as a first treatment choice. In addition, the non-operative treatment seems to show good results also in treatment-resistant patients.