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

Income level was judged only from the country of the corresponding author's institution and only from gross national income per capita. The study did not look at other things that affect trial quality, such as who funded a trial or industry sponsorship, or the research expertise, technology and institutional support available to the team. Countries were classified using the World Bank's 2020 income list regardless of when each trial was published, so a country's category may not match its category at the time the trial was done. The PEDro scale was designed for randomised trials and may score trials containing an economic evaluation poorly, although fewer than 2% of the included trials were economic evaluations. Only three databases were searched, and the authors acknowledge they may have missed trials from low- and lower-middle-income countries published in languages other than English, in local journals or as grey literature. Most included trials came from a small number of countries.

The authors declare no competing interests. The supplied text contains no funding statement, so who paid for the work is not reported here.

Do not read this as evidence that physical therapy for low back pain is worse, or better, in poorer countries. The study only scored how trials were conducted, not how patients responded, and the gap it found was 0.7 points on a 10-point scale. It also cannot tell you whether an individual trial from a low- or lower-middle-income country is trustworthy, only what the average looks like across 2552 trials.