Association of pet ownership and incident depression^(a) risk of participants in Nurses’ Health Study 2 who were free of depression at baseline and reported on pet ownership, stratified by chronotype^(b).

Risk estimates are odds ratios (OR) with 95% confidence intervals (CI). (N = 26,169).风险估计值为带有95%置信区间（confidence interval，CI）的比值比（odds ratio，OR）。（样本量N=26,169）