Five different stories behind an average improvement in pain

An analysis of a British registry of 3,744 chronic pain patients found improvements in average pain, sleep and quality-of-life measures over two years of treatment with cannabis-based medicines. Researchers identified five different trajectories, however: in one group, pain had almost returned to its starting level by the end. Actual pain-severity scores at two years were available for about one-third of participants, with missing values statistically imputed. Adverse events were recorded in 538 people, predominantly mild or moderate; the study had no control group, so it cannot separate treatment effects from expectations and sample characteristics.