Association of admission-to-surgery timing with 90-day readmission after cauda equina syndrome: a Nationwide Readmissions Database retrospective cohort study

Cauda equina syndrome (CES) is a time-sensitive spinal emergency. We examined whether admission-to-surgery timing is associated with observable 90-day readmission after non-elective CES hospitalization. We analyzed the 2020–2022 Nationwide Readmissions Database, retaining the first CES hospitalization per patient within each calendar year. Adults discharged alive in quarters 1–3 after non-elective decompression/discectomy were grouped by surgery on hospital day 0, day 1, or day ≥ 2. Discharge-weighted logistic regression incorporated hospital-year clustering and year-specific strata within the source extract. Unweighted propensity score matching was exact on calendar year, with standard errors clustered by matched pair and hospital-year. Sensitivity analyses examined finer timing categories, coding definitions, fusion, and missingness. Among 8269 surgical admissions, weighted observable readmission was 14.6, 16.3, and 26.7% for days 0, 1, and ≥ 2, respectively. The crude absolute difference for day ≥ 2 versus day 0 was 12.1% points. In 8,133 complete records, the adjusted odds ratio was 1.63 (95% confidence interval 1.41–1.89); day 1 was not significantly different from day 0. Matching produced 1,801 pairs; readmission was 23.9% versus 17.7% (odds ratio 1.47, 95% confidence interval 1.25–1.72), with a maximum absolute post-match standardized mean difference of 0.046. Admission-relative surgery on hospital day ≥ 2 was associated with greater observable 90-day readmission, extending CES timing research to postdischarge utilization. This timing category may identify a higher-risk inpatient group for further study of perioperative and discharge care; it does not establish that changing timing would prevent readmission or define a symptom-onset neurologic threshold. Cauda equina syndrome affects nerves in the lower spine and can impair bladder, bowel, and leg function. We studied whether the day of surgery after hospital admission was linked to returning to hospital within 90 days of discharge. We analyzed 8269 non-elective surgical hospital stays in a US database from 2020 to 2022. Recorded readmission occurred in about 15% of stays with surgery on the admission day, compared with 27% when surgery occurred on hospital day 2 or later. The association remained after accounting for recorded patient differences. These findings do not show that waiting caused readmission. Patients operated on later may have been more medically complex, and the database lacks detailed nerve examinations and the time symptoms began. Readmissions in another state were not captured. The results may help guide future research on discharge support, but do not justify delaying urgent treatment. This summary accompanies the scientific abstract and does not replace it.