Impact of the COVID-19 Pandemic on Primary Care Referral Patterns and Resource Utilization in a Hospital Emergency Department: A Comparative Pre- and Later-Pandemic Study.

BACKGROUND

The COVID-19 pandemic profoundly disrupted healthcare utilization patterns at both primary care (PC) and hospital emergency department (ED) levels. This study aimed to assess the impact of the pandemic on referral patterns from PC to a hospital ED and on the resource consumption associated with those referrals.

METHODS

A descriptive, retrospective, longitudinal comparative study with multivariable sensitivity analyses was conducted at a first-level hospital of Madrid (Spain). All consecutive PC-to-ED referrals received during two observation windows were included: a pre-pandemic period (1 June-31 December 2019; n=946) and a Later-Pandemic period (1 January-30 June 2022; n=1797). Sociodemographic characteristics, referral form quality, diagnostic specialty, and in-ED resource utilization variables were collected and compared using χ2, Student's t-test, and Mann-Whitney U tests as appropriate. To assess seasonal confounding, multivariable logistic and ordinal regression models adjusting for calendar season, age, and sex were performed for the primary resource-utilization outcomes.

RESULTS

A total of 2743 referrals were analyzed. The monthly referral rate increased by approximately 122% between periods (135/month vs. 300/month). A statistically significant but clinically negligible difference in mean age was observed (53.1±18.3 vs. 54.9±19.0 years; p=0.015); no significant sex differences were found. Referral form completion improved significantly for clinical history (94.5% vs. 98.2%; p<0.001). Orthopedics referrals nearly tripled (5.8% vs. 18.4%), while respiratory/COVID-19-related referrals represented 22.0% of the 2022 caseload. ED length of stay between 3 and 6 h increased from 13.0% to 42.8% (p<0.001), while the need for urgent blood tests fell from 68.9% to 56.0% (p<0.001), hospital admission from 68.4% to 10.9% (p<0.001), and referral to another center from 12.3% to 0.9% (p<0.001). In multivariable sensitivity analyses, the period effect remained statistically significant after adjustment for calendar season, age, and sex for hospital admission (adjusted OR =0.062; 95% CI: 0.037-0.106; p<0.001) and urgent blood test utilization (adjusted OR =0.470; 95% CI: 0.326-0.678; p<0.001), although study period and season remain partly confounded by the non-overlapping design.

CONCLUSIONS

During the later-pandemic period, PC-to-ED referrals increased substantially while being associated with fewer complementary investigations and fewer hospital admissions. This study documents between-period differences in referral patterns and ED resource utilization rather than causal effects; the differences persisted after adjustment for seasonality but cannot be definitively attributed to the pandemic. Future multi-center longitudinal studies are needed to confirm these trends and clarify their underlying mechanisms.