Reductions in indoor tanning could be attributed to several factors.

The study used existing publicly available and deidentified data The Stanford institutional review board deemed this study exempt as it uses deidentified, administratively collected data. The HPS contains the Patient Health Questionnaire-4 (PHQ-4), a well-established and validated screening tool for anxiety and depression. HPS public-use files were used to construct the analytic sample. School of Public Health Institutional Review Board deemed this study exempt. Several study limitations should be acknowledged. Ethical approval was not sought as the data were already publicly available online. We checked the robustness of our findings The aim of this study was twofold. This systematic review and meta-analysis includes previously published observational studies. This indicated there was no requirement for proceeding to a full formal ethics and data protection review by the Usher Research Ethics Group. No overall prospective analysis plan was used. Complete case analyses were used. Study approval was received from Institutional Review Boards (IRBs) of the primary research institution These findings must be interpreted in light of several limitations