Bisphosphonates for treatment of Complex Regional Pain Syndrome type 1: A systematic literature review and meta-analysis of randomized controlled trials versus placebo

Objectives: Complex Regional Pain Syndrome Type 1 is a severely disabling pain syndrome with no definite established treatment. We have performed a systematic literature review and meta-analysis of all randomized controlled trials to assess the benefit of bisphosphonates on pain and function in patients with Complex Regional Pain Syndrome Type 1.

Methods: A systematic literature search was performed in the Medline, Embase and Cochrane databases. Two authors selected independently blinded randomized trials comparing bisphosphonates to placebo on short-term (J30 to J40) and medium term pain (M2-M3), safety and function in patients with CRPS 1. The methodological quality of the studies was analyzed. Data were aggregated using the method of the inverse of the variance.

Results: 258 articles were identified. Four trials of moderate to good quality comprising 181 patients (90 in the bisphosphonate group and 91 in the placebo group) were included in this meta-analysis. Short-term pain Visual Analog Scale was significantly lower in the bisphosphonate group versus the placebo group (SMD=-2.6, 95%CI [-1.8, -3.4], P<0.001), as well as the medium term Visual Analog Scale pain (SMD=-2.5, 95%CI [-1.4, -3.6], P<0.001). There were more adverse events in the bisphosphonate group (35.5%) than in the placebo group (16.4%) with a relative risk of 2.1 (95%CI [1.3, 3.5], P=0.004) and a number needed to harm of 4.6, (95%CI [2.4, 168.0]) but no serious side effects.

Conclusions: Our results suggest that bisphosphonates reduce pain in patients with Complex Regional Pain Syndrome type 1. Other studies are needed to determine their effectiveness.