PLoS One 2025 (Jan 28); 20 (1): e0317663

Table 1. Baseline characteristics before and after propensity matching.

	Before matching			After matching
Variable	CSM	Usual medical care	SMD	CSM	Usual medical care	SMD
N	372471	2090255	NA	372471	372471	NA
Demographics
Age, mean (SD)	51.5 (15.8)	52.5 (14.9)	0.066	51.5 (15.8)	51.4 (15.7)	0.005
Female, n (%)	219762 (59%)	1324739 (63%)	0.090	219762 (59%)	220391 (59%)	0.003
Male, n (%)	152595 (41%)	764830 (37%)	0.090	152595 (41%)	151991 (41%)	0.003
Hispanic or Latino, n (%)	4234 (1%)	63957 (3%)	0.134	4234 (1%)	4252 (1%)	<0.0001
Not Hispanic or Latino, n (%)	90376 (24%)	591987 (28%)	0.092	90376 (24%)	89332 (24%)	0.007
Asian, n (%)	540 (<1%)	5541 (<1%)	0.027	540 (<1%)	477 (<1%)	0.005
Black or African American, n (%)	4529 (1%)	108600 (5%)	0.227	4529 (1%)	4645 (1%)	0.003
White, n (%)	85263 (23%)	491039 (23%)	0.014	85263 (23%)	83955 (23%)	0.008
Comorbidities, n (%)
Adverse socioeconomic and psychosocial circumstances	3806 (1%)	53255 (3%)	0.115	3806 (1%)	3247 (1%)	0.015
Alcohol related disorders	3211 (1%)	60113 (3%)	0.149	3211 (1%)	2968 (1%)	0.007
Chronic kidney disease	7249 (2%)	95258 (5%)	0.148	7249 (2%)	7007 (2%)	0.005
Chronic obstructive pulmonary disease	8006 (2%)	158164 (8%)	0.254	8006 (2%)	7962 (2%)	0.001
Diabetes mellitus	37912 (10%)	392601 (19%)	0.246	37912 (10%)	37536 (10%)	0.003
Diseases of liver	6679 (2%)	83893 (4%)	0.133	6679 (2%)	6269 (2%)	0.008
Hypertensive diseases	87373 (23%)	804219 (38%)	0.329	87373 (23%)	87509 (23%)	0.001
Mood disorders	31189 (8%)	366957 (18%)	0.276	31189 (8%)	31112 (8%)	0.001
Nicotine dependence	13392 (4%)	295931 (14%)	0.378	13392 (4%)	13669 (4%)	0.004
Osteoarthritis	15029 (4%)	178523 (9%)	0.186	15029 (4%)	14577 (4%)	0.006
Sedative, hypnotic, or anxiolytic related disorders	201 (<1%)	7622 (<1%)	0.068	201 (<1%)	188 (<1%)	0.002
Substance use disorders	17754 (5%)	380971 (18%)	0.432	17754 (5%)	17606 (5%)	0.002
Medications, n (%)
Medications (any)	199678 (54%)	1354075 (65%)	0.229	199678 (54%)	199156 (53%)	0.003
Alcohol deterrents	513 (<1%)	4977 (<1%)	0.023	513 (<1%)	324 (<1%)	0.015
Gabapentin	9347 (3%)	206179 (10%)	0.309	9347 (3%)	9179 (2%)	0.003
Naloxone	105 (<1%)	8814 (<1%)	0.083	105 (<1%)	199 (<1%)	0.012
Naltrexone*	436 (<1%)	4002 (<1%)	0.019	436 (<1%)	268 (<1%)	0.015
Opioid analgesics	48633 (13%)	619773 (30%)	0.413	48633 (13%)	49372 (13%)	0.006
Sedatives/hypnotics	30780 (8%)	316465 (15%)	0.215	30780 (8%)	30435 (8%)	0.003
Skeletal muscle relaxants	21527 (6%)	330189 (16%)	0.327	21527 (6%)	21466 (6%)	0.001
Procedures, n (%)
Anesthesia	28046 (8%)	251928 (12%)	0.153	28046 (8%)	27595 (7%)	0.005
Surgery	175569 (47%)	1250514 (60%)	0.256	175569 (47%)	175628 (47%)	<0.0001

Abbreviations:

chiropractic spinal manipulation (CSM),
standard deviation (SD),
standardized mean deviation (SMD)

Variable displayed for descriptive purposes–not matched