Table 1. Variable description.

	Variables	Type	Description
Response Variable	Length of Stay (LOS)	Continuous	Length of stay post surgery in hours
NSQIP Variables [39]	Procedure	Categorical	Total Knee (TKA), Total Hip (THA), Total Shoulder (TSA) Arthroplasty
	Age	Continuous	Patient age in years
	Sex	Dichotomous	Gender: Male, Female
	Functional Status	Ordinal	Fully Independent (1), Partially independent (2), Fully dependent (3)
	ASA Class	Ordinal	Healthy patient (1), Mild systemic disease (2), Severe systemic disease (3), Severe disease with constant threat to life (4)
	Diabetes	Dichotomous	No (1), Yes (2)
	Hypertension	Dichotomous	No (1), Yes (2)
	Current Smoker within 1 year	Dichotomous	No (1), Yes (2)
	BMI	Continuous	Body Mass Index in Kg/m2
Additional variables	Duke Activity Status Index [40]	Continuous	Functional capacity scaled from 2.74 (low functional activity) to 9.89 (high functional activity) in METs
	Living Status [45]	Dichotomous	Patient’s primary household status—lives alone, living with another
	Patient’s Household Income [42]	Ordinal	Patient’s household income level: <$49K (1), $50-99k (2), $100+k (3)
	Postoperative Nausea and Vomiting Score (PONV) [41]	Ordinal	To estimate nausea after surgery due to anesthesia, scaled 0 (low chances of nausea) to 4 (high chances of nausea)
	Depression [3]	Dichotomous	Depression at the time of preoperative assessment: No (1), Yes (2)
	Preoperative Engagement Period [49]	Discrete -Ordinal	Difference in time period (in days)
	Patient Insurance Type [50]	Dichotomous	Patient’s payer—Public, Private type
	Distance Travelled by the patient [44]	Continuous	Distance traveled by the patient from their resident to the hospital (in miles)