Study objective: To determine whether emergency department complaint frequency varies with patient median household income, as approximated by patient residence zip code.
Design: All patient visits and complaints received in one ED were reviewed. Median household income of patient residence zip codes was obtained from available demographic data. Patients were categorized into seven income categories.
Exclusions: Cases in which zip codes could not be determined or zip code income data could not be obtained; complaints from physicians, not patients; and data from zip codes remote from the hospital.
Setting: Nine hundred twenty-nine-bed teaching hospital.
Type of participants: All ED visits and all ED complaints over a four-year period.
Statistical analysis: Armitage's chi 2 test for trend of proportions was used to compare complaint frequencies in different income groups.
Results: A total of 277,210 patient visits and 675 complaints met study criteria. Complaint frequencies ranged from 1.65 to 3.14 per thousand visits. Higher-income patients were more likely to complain than lower-income patients (P = .0000058).
Conclusion: In this setting, ED patients residing in higher median income zip codes are more likely to register complaints than those from lower-income zip codes. Complaint frequencies from hospitals with different demographics may not be comparable.