Abstract: We included 13 trials in this Cochrane review. Ten studies were at 'low' risk of bias. Six studies compared NSAIDs with placebo, and included 1354 participants in total. There is low quality evidence that NSAIDs are more effective than placebo, with a mean difference in pain intensity score from baseline of -6.97 (95% CI −10.74 to −3.19) on a 0 to 100 visual analogue scale (VAS) with a median follow-up of 56 days (interquartile range (IQR) 13 to 91 days). Four studies measured disability using the Roland Morris Disability Questionnaire. There is low quality evidence that NSAIDs are more effective than placebo on disability, with a mean difference from baseline of −0.85 (95% CI −1.30 to −0.40) on a scale from 0 to 24 with a median follow-up of 84 days (IQR 42 to 105 days). All six placebo controlled studies also reported adverse events, and suggested that adverse events are not statistically significant more frequent in participants using NSAIDs compared to placebo (RR 1.04, 95% CI 0.92 to 1.17). Due to the relatively small sample size and relatively short follow-up in most included trials, it is likely that the proportion of patients experiencing an adverse event is underestimated. Two studies compared different types of non-selective NSAIDs, namely ibuprofen versus diclofenac and piroxicam versus indomethacin. The trials did not find any differences between these NSAID types, but both trials had small sample sizes. One trial reported no differences in pain intensity between treatment groups that used selective or non-selective NSAIDs. One other trial compared diflunisal with paracetamol and showed no difference in improvement from baseline on pain intensity score. One trial showed a better global improvement in favour of celecoxib versus tramadol. One included trial compared NSAIDs with 'home-based exercise'. Disability improved more in participants who did exercises versus participants receiving NSAIDs, but pain scores were similar. Six of the 13 included RCTs showed that NSAIDs are more effective than placebo regarding pain intensity. NSAIDs are slightly more effective than placebo regarding disability. However, the magnitude of the effects is small, and the level of evidence was low. When we only included RCTs at low risk of bias, differences in effect between NSAIDs and placebo were reduced. We identified no difference in efficacy between different NSAID types, including selective versus non-selective NSAIDs. Due to inclusion of RCTs only, the relatively small sample sizes and relatively short follow-up in most included trials, we cannot make firm statements about the occurrence of adverse events or whether NSAIDs are safe for long-term use.

Plain-language summary: We collected all published randomized controlled trials evaluating the efficacy of NSAIDs until 24 June 2015. We included 13 trials which compared NSAIDs with placebo, other NSAIDs, other drugs or other treatment in people with chronic low back pain. Six trials compared NSAIDs with placebo, and included 1354 participants in total. Follow-up was between nine days and 16 weeks. NSAIDs reduced pain and disability in people with chronic low back pain compared to placebo. However, the differences were small: 7 points on a 100-point scale for pain intensity. Regarding disability, people receiving NSAIDs scored 0.9 points better on a 0 to 24 disability scale. The number of adverse events was not significantly different between the people receiving NSAIDs and people receiving placebo, but larger studies of longer duration would be needed to identify rare or delayed adverse events, important drug interactions and adverse events occurring with prolonged use. Different types of NSAIDs did not show significantly different effects. Three of the 13 included studies compared two different types of NSAIDs and none found any differences. NSAIDs were also compared to other drug types: paracetamol, tramadol and pregabalin. There were no differences found between NSAIDs and paracetamol and pregabalin in either effect or adverse events. A single study comparing celecoxib with tramadol showed a better global improvement in peoples using celecoxib. One trial compared NSAIDs with 'home-based exercise'. Regarding disability, people who did exercise improved more than people receiving NSAIDs, but pain scores were not statistically different. There was low quality evidence that NSAIDs are slightly more effective than placebo in chronic low back pain. The magnitude of the difference was small, and when we only accounted for trials of higher quality, these differences reduced.