The methodological quality of clinical trials of physical therapy for low back pain varies between countries with different income levels. A meta-epidemiological study.

Background: Low back pain is a severe global health problem. To face this issue, testing interventions using rigorously performed randomized controlled trials is essential. However, it is unclear if a country's income level is related to the quality of trials conducted.

Objective: To compare the frequency and methodological quality of randomized controlled trials of physical therapy interventions for low back pain conducted in countries with different income levels.

Methods: This meta-epidemiological study retrieved trials from the Physiotherapy Evidence Database (PEDro), Literatura Latino Americana em Ciências da Saúde (LILACS), and Scientific Electronic Library Online (SciELO). The methodological quality was evaluated using the 0-10 PEDro scale. Then we calculated the mean differences with a 95% confidence interval and performed an ANOVA test with Bonferroni correction to compare the PEDro scores between income groups.

Results: We included 2552 trials; 70.4% were conducted in high-income countries. The mean (standard deviation) PEDro score of all trials was 5.5 (0.03) out of 10. Trials from low- or lower-middle-income countries had lower methodological quality than those from upper-middle- and high-income countries, but the mean difference was small (-0.6 points (95% CI -0.9, -0.3), and -0.7 points (95% CI -1.1, -0.5) respectively).

Conclusion: Income level influences the methodological quality of trials of physical therapy intervention but is not the only factor. Implementing strategies to improve the methodological rigor of trials in patients with low back pain is necessary in all countries, regardless of income level.