No long-term effects after a three-week open-label placebo treatment for chronic low back pain: a three-year follow-up of a randomized controlled trial

Chronic low back pain is prevalent, highly disabling and a relevant socioeconomic health concern. Although allocated to placebo groups, patients in randomized controlled trials show significant pain relief, pointing to the relevance of placebo effects. Overcoming ethical and legal concerns related to deceptive placebos, recent studies have demonstrated the efficacy of short-term treatments for chronic low back pain with open-label (i.e., non-deceptive) placebos. However, data on long-term efficacy of open-label placebos are sparse. Here, we report a three-year follow-up of our previously published randomized controlled trial demonstrating pain reduction, improvement in disability and depressive symptoms after a three-week treatment with open-label placebos. Including records from N=89 previously enrolled patients, we investigated changes between the groups with and without previous open-label placebo treatment in pain intensity (primary outcome), disability and mood (secondary outcomes), biopsychosocial factors and lifestyle (exploratory outcomes) from parent baseline to follow-up. Over the three-year period, there were no differences in any outcome between groups with and without open-label placebo treatment. Therefore, our follow-up data do not support the previously suggested assumption that a three-week open-label placebo treatment has long-term effects. This study was pre-registered on April 14, 2020, in the German Clinical Trials Register (registration number DRKS00021405).