Who uses multiple hospitals for care? Demographic considerations using 4 years of statewide, all-payer hospitalization data

Background: This study considered the demographic characteristics of individuals using multiple hospitals compared to those using one hospital for care over a 4-year period. Methods: Hawaii Health Information Corporation (HHIC) adult data from December 2006-December 2010 was used, which includes detailed discharge information for all hospitalizations in Hawaii. Chi-squared tests and multivariate logistic regressions compared individuals using 1 hospital vs. multiple hospitals. Transfers and those not from Hawaii and/or missing race/ethnic or payer data were excluded. Statistical significance is at the p<0.0001 level unless otherwise noted. Results: Out of 289,190 hospitalizations from 168,143 unique individuals, 18,300 individuals (11.8%) used multiple hospitals. Of these, 16,234 (9.7% of total) used two hospitals, 1817 (1.1%) used three hospitals, and 249 (<1%) used 4 or more hospitals. Of note, many individuals (65%) in the sample only had one hospitalization during the study period. Of the 88,398 individuals with >1 hospitalizations, 20.7% used multiple hospitals. Men (14.4%) were significantly more likely than women (10.2%) to use multiple hospitals, as were older individuals (15.1% if 65+ years, 12.7% if 40-64, and 6.8% if 18-39) and those on Medicare (16.2%) and Medicaid (12.8%) vs. private insurance (8.0%). Native Hawaiians had the highest likelihood of using multiple hospitals (12.7%), followed by Japanese (12.1%), White (11.7%), Filipino (11.1%) and Chinese (10.8%). Those using multiple hospitals had significantly higher comorbidity scores (3.96) than those using one (2.02). Importantly, 43.2% of those who changed insurance during the time period (4% of the sample) used multiple hospitals as did 87.9% of those who changed residence to another county/island (<1% of the sample). In multivariable adjusted analysis results, females remained significantly less likely than males (OR:0.90; 95%CI:0.87-0.93) to use multiple hospitals as did Chinese (OR:0.84; 95%CI:0.78-0.91) and Japanese adults (OR:0.95; 95%CI: 0.91-0.99;p<.05) compared to Whites. Older age significantly (p<.01) predicted multiple hospitals as did Medicaid (OR:1.72; 95%CI:1.64-1.81) and Medicare (OR: 2.31; 95%CI: 2.17-2.45) vs. private insurance, and higher comorbidity scores (OR: 1.22; 95%CI: 1.21-1.22). Both payer change (OR:6.46; 95%CI:6.01-6.80) and island residence change (OR:47.15; 95%CI:37.54-59.23) were strongly and significantly associated with multiple hospital use. Conclusions: Over 10% of patients tracked by HHIC used multiple hospitals, with particularly high percentages (>15%) seen among the elderly, those on Medicare, and in individuals who changed payer or islands. Analyses that do not track hospitalizations across multiple hospitals may lose key utilization information, particularly for the elderly, Medicare, men, or individuals with unstable residence or insurance.