Comparing the Kids' Inpatient Database and National Inpatient Sample for Pediatric Research

Area of Science:

• Pediatric Health Services Research
• Health Informatics
• Biostatistics

Background:

• Pediatric researchers utilize the Agency for Healthcare Research and Quality (AHRQ) Kids' Inpatient Database (KID) and National Inpatient Sample (NIS) for analyzing national pediatric inpatient resource use and outcomes.
• Inherent differences in the sampling designs of KID and NIS may lead to disparate research findings.

Purpose of the Study:

• To compare discharge counts and length of stay (LOS) between the KID and NIS for common and rare pediatric hospital admission reasons.
• To identify potential discrepancies in national estimates derived from these two large pediatric inpatient databases.

Main Methods:

• A retrospective analysis was conducted on 2019 data for children aged 0-20 years from KID and NIS.
• Discharge counts and geometric mean LOS were compared for normal newborns and 331 other admission reasons, categorized by All-Payer Refined Diagnosis Related Groups (APR-DRG) and deciles of annual discharge volume.
• Data were analyzed following AHRQ guidelines for clustering, stratification, and weighting to account for the distinct sampling designs of KID and NIS.

Main Results:

• National estimates for total annual discharge counts showed minimal differences: 0.5% for normal newborns and 3.7% for other admission reasons.
• Discrepancies in discharge counts increased for admission reasons in the two lowest volume deciles (<520 discharges): 9.5% (SD 7.9%) for 200-520 volumes and 41.1% (SD 64.2%) for <200 volumes.
• Length of stay (LOS) differences for these lowest volume deciles were 7.9% (SD 7.1%) and 26.0% (SD 29.3%), respectively.

Conclusions:

• While KID and NIS yield similar results for high-volume pediatric admissions, significant differences emerge for admissions with annual volumes of approximately 500 or less.
• For analyses involving study populations with fewer than 500 discharges, the KID may be the preferred database due to its higher sampling rate of pediatric discharges per hospital.