Length of stay is one of the metrics of crowding in the emergency department. Identification of the factors associated with prolonged length of stay is vital for staffing and policy making to prevent overcrowding at the ambulatory care unit.

This study aimed to determine the association of sociodemographic, clinical, and temporal factors with length of stay among patients seen at the ambulatory care unit of a tertiary government training hospital.

A retrospective case-control study was conducted between January to December 2019 at the ambulatory care unit of a tertiary government hospital. Charts of patients who stayed for more than six (6) hours were classified as cases, while those who stayed for more than two (2) hours up to six (6) hours were classified as controls. Charts were reviewed to obtain the clinicodemographic profile of patients who satisfied the inclusion criteria.

The case group consisted of 86 patients, while the control group consisted of 172 patients. Eight factors had an effect on the probability of prolonged length of stay at the ambulatory care unit: age 40-59 years old (OR = 2.29, 95% CI: 1.16-4.49), ESI 3 at triage level (OR = 3.35, 95% CI: 1.50-8.38), psychiatric complaint (OR = 6.97, 95% CI: 2.53-19.21), medications given and diagnostics done (OR = 2.16, 95% CI: 1.16-3.99), medications given/diagnostics/ referral to other services done (OR = 7.67, 95% CI: 2.70-21.80), psychiatric/substance-related case (OR = 6.97, 95% CI: 2.63-18.49), transferred to other services (OR = 3.25, 95% CI: 1.33-7.94), and endorsed to next shift (OR = 6.94, 95% CI = 3.90-12.35).

The factors associated with prolonged length of stay were middle-aged adults, conditions with severe presentation, psychiatric/substance-use-related cases, need for more diagnostic test and treatment intervention, and decision to transfer care to other services.