Fig. 6. Impact of drug class on the development of chronic pain in humans.

Forest plots track odds ratios (OR; log₂ scaled) for the acute-to-chronic transition of back pain and several factors, including analgesic drug classes (up-pointing triangle; green), demographics (down-pointing triangle; brown), possible confounding factors (circle; blue), and percent of neutrophils (lozenge; pink). Models 1 to 3 test each analgesic drug class separately (gray background when factor is not included in the model), whereas model 4 tests all analgesic drug classes simultaneously. Model 5 takes into account possible confounding factors for analgesic drug intake. Model 6 includes neutrophil percentages. Vertical gray bars indicate OR = 1 [log₂(OR) = 0]. ORs are indicated by dots inside shapes, whereas the 95% confidence intervals for OR are indicated by horizontal bars. Horizontal bars are filled when P < 0.05. *P < 5 × 10⁻² and **P < 5 × 10⁻³.