Table 6.

Subgroup analysis.

Variables	Categories/range	Pain intensity*						Depressive symptoms
		Stable severe and moderate vs other trajectories (n = 67)		U-shape vs other trajectories		Inverted U-Shape vs other trajectories		Severe slightly improving or stable moderate trajectories vs other trajectories		Stable mild vs other trajectories		Stable very mild or none vs other trajectories
		OR (95% CI)	P	OR (95% CI)	P	OR (95% CI)	P	OR (95% CI)	P	OR (95% CI)	P	OR (95% CI)	P
Cortisol variable
Percentage of change in cortisol, pg/mg	−60.5 to 250	1.0 (1.0, 1.0)	0.547	1.0 (1.0, 1.0)	0.630	1.0 (1.0, 1.0)	0.690	1.0 (1.0, 1.0)	0.722	1.0 (1.0, 1.0)	0.753	1.0 (1.0, 1.0)	0.413
Pre–COVID-19 variables
Pain intensity before COVID-19	Score from 0 = No pain to 10 = worst imaginable pain)	1.3 (0.8, 2.2)	0.269	1.4 (0.7, 2.7)	0.389	0.7 (0.5, 1.2)	0.202	0.8 (0.3, 1.9)	0.612	0.9 (0.5, 1.4)	0.571	1.5 (0.8, 2.9)	0.248
Depressive symptoms before COVID-19	T score from 41.0 to 79.4	1.0 (0.9, 1.1)	0.996	1.0 (0.9, 1.2)	0.553	1.0 (0.9, 1.1)	0.819	1.3 (1.0, 1.5)	0.036	1.1 (1.0, 1.2)	0.210	0.9 (0.8, 1.0)	0.035
Pain interference before COVID-19	T score from 41.6 to 75.6	1.0 (0.8, 1.1)	0.597	0.9 (0.7, 1.1)	0.244	1.0 (0.9, 1.2)	0.841	1.1 (0.8, 1.6)	0.448	1.0 (0.8, 1.2)	0.788	0.9 (0.8, 1.2)	0.612
Physical function before COVID-19	T score from 22.9 to 56.9	0.7 (0.5, 0.9)	0.007	1.1 (0.9, 1.4)	0.262	1.0 (0.8, 1.2)	0.961	1.1 (0.8, 1.5)	0.556	1.0 (0.8, 1.2)	0.716	1.1 (0.9, 1.4)	0.441
Onset-of-pandemic variables
Age in years	Years	1.0 (0.9, 1.1)	0.730	1.0 (0.9, 1.1)	0.919	1.0 (1.0, 1.1)	0.584	1.0 (0.9, 1.1)	0.613	1.0 (0.9, 1.0)	0.544	1.1 (0.9, 1.1)	0.728
Acute stress disorder	Score from 0 to 76	1.1 (1.0, 1.2)	0.098	0.9 (0.8, 1.0)	0.192	1.0 (0.9, 1.1)	0.930	1.1 (1.0, 1.3)	0.098	1.0 (1.0, 1.1)	0.337	0.8 (0.7, 0.9)	0.004
Finding the COVID-19 pandemic stressful	Score from 0 (not at all) to 10 (extremely)	1.2 (0.9, 1.6)	0.262	1.2 (0.8, 1.9)	0.328	0.7 (0.5, 1.0)	0.038	1.7 (0.9, 3.3)	0.131	0.8 (0.6, 1.2)	0.313	1.2 (0.7, 1.9)	0.537
Finding lockdown measures associated with the COVID-19 pandemic stressful	Score from 0 (not at all) to 10 (extremely)	1.0 (0.8, 1.4)	0.677	0.9 (0.6, 1.3)	0.513	1.0 (0.8, 1.4)	0.783	1.2 (0.7, 2.0)	0.529	1.1 (0.8, 1.5)	0.403	0.8 (0.6, 1.3)	0.393
Methodological variable
Months between pre–COVID-19 and baseline surveys	0–17 mo	1.0 (0.8, 1.2)	0.753	1.0 (0.8, 1.2)	0.716	1.1 (0.9, 1.2)	0.434	0.9 (0.8, 1.1)	0.347	1.1 (0.9, 1.2)	0.428	1.0 (0.8, 1.2)	0.809
Model evaluation
Hosmer and Lemeshow test		0.954		0.533		0.789		0.268		0.032		0.339

Association between cortisol and pain intensity trajectories and depressive symptoms adjusted for several variables.

^*Stable mild pain (n = 5) vs other trajectories (n = 62) were not included because of small sample size.