Methods: We analyzed data from the National Hospital Ambulatory Medical Care survey for 1997 to 2007. We used multivariate binary and polytomous survey-adjusted logistic regression to determine the effect of predictors on the odds of ED visits occurring during specified times.
Results: Overall, 34% of NTDC visits occurred on weekends and 29% weekdays 8am-5pm. Compared to proportions expected if visits were uniformly distributed, the largest differences were observed on weekend daytime and evenings (50-60% more) and at nights (20-30% fewer). Payer type was the only significant univariate predictor of the odds of an NTDC visit occurring on a weekend. Age, payer type, and reason for visit showed significant association with the time of day of the visits. Compared to 19-33 year olds, patients <18 were more likely to visit outside working hours (ORs ranging from 1.3 to 2.3, with the exception of under-5 year olds for weekend night), while those 34-52 were less likely to go during evenings and nights (all ORs close to 0.7; overall p=0.0003). Compared to those with private insurance, patients with Medicaid and self-pay patients were less likely to come outside working hours (ORs from 0.5 to 0.8, overall p<0.0001).
Conclusions: This study suggests that NTDC visits were more likely to occur at weekends and less likely to occur at nights. The day and time of day of the NTDC visits was associated with payer type and age.
Keywords: Access, Emergency Department, Health services research and Utilization/demand