Outcome measures
Emergency department visits and inpatient admissions were designated as high-cost encounters because of their potential for high use, accounting for a significant portion of non-surgical cost for HMO members, and a high likelihood of lack of follow-up after the encounter. Review of HMO financial data revealed these to be members’ highest (nonsurgical) costs. A calculated variable: A high-cost encounter was calculated by determining a binary outcome variable derived by aggregating emergency department and inpatient visits.
Data analysis
The study groups were compared by logistic regression. The 95% confidence intervals (CIs) accompanying the odds ratios (ORs) are the tests of significance. If the range of the CI includes the value 1, the difference between groups being compared is not statistically significant (α=.05).
Results
Table 2 shows the OR of a high-cost encounter (emergency department visit or inpatient admission) for each intervention group. The unit of measure for this table is patient-months.7,8 All ORs are read from left to right. For example, the minimal intervention group is 2.19 times more likely to have an emergency department event than maximal group.
The risk of a high-cost encounter was significantly greater for the minimal intervention than for the moderate or maximal intervention groups. The moderate group had a statistically significant greater risk of a high-cost encounter than the maximal intervention group, but the observed magnitude of the risk was small and the lower limit of the CI is very close to 1. The clinical importance of this finding may be questioned in light of the cost effectiveness of the maximal intervention.
The probability of an emergency department visit was significantly reduced for minimal compared with moderate and maximal intervention. The risk for emergency department events was the same for the moderate and maximal intervention groups.
The minimal group was more likely to have an admission than both the moderate and maximal intervention groups. The maximal group was also less likely to have an admission than the moderate intervention group. The moderate intervention appears to be the most costeffective because of reductions achieved with minimal staff involvement.
TABLE 2
Odds ratio of high-cost encounter* for each intervention group
| High-cost encounters (patient-months) | Emergency department use | Inpatient admissions | ||||
|---|---|---|---|---|---|---|
| Comparison | OR | 95% CI | OR | 95% CI | OR | 95% CI |
| Control vs minimal | 1.32 | (1.20–1.60) | 1.32 | (1.20–1.60) | 1.60 | (1.42–2.43) |
| Control vs moderate | 1.83 | (1.56–2.14) | 2.46 | (1.80–3.38) | 2.64 | (1.92–3.64) |
| Control vs maximal | 2.31 | (1.95–2.73) | 2.91 | (2.12–4.01) | 4.37 | (3.15–6.06) |
| Minimal vs moderate | 1.39 | (1.19–1.61) | 1.85 | (1.39–2.46) | 1.64 | (1.24–2.17) |
| Minimal vs maximum | 1.75 | (1.49–2.00) | 2.19 | (1.64–2.92) | 2.71 | (2.02–3.62) |
| Moderate vs maximum | 1.26 | (1.06–1.50) | 1.18† | (0.88–1.59) | 1.65 | (1.23–2.21) |
| *High-cost encounter defined as emergency department visit or inpatient admission. | ||||||
| †Nonsignificant. | ||||||
| OR, odds ratio; CI, confidence interval | ||||||
Physician acceptance
All physicians in the 3 intervention groups were surveyed after study completion. Ninety percent agreed with the statement “I will use the moderate intervention now that it is shown to reduce utilization.”
Maximal intervention was thought to be less useful because many patients contacted were under the care of specialists and had no intention of returning to the primary care physician for care. Most of these patients did not require the use of the care manager, so the primary care physicians considered this extra expense as unnecessary.
Discussion
Our results appear to support the contention that primary care physicians can use relatively simple methods to monitor and modify the highuse behavior of members of their managed care panels. By designating frequent users of medical services as “high risk” for future utilization, primary care physicians can track these patients in a proactive fashion using a real-time database system.
At least in this relatively large, vertically integrated, multispecialty health system, emergency department and inpatient admissions were significantly reduced using the database. The moderate intervention appeared to be relatively well accepted by the primary care physicians and able to be instituted within their practice without much difficulty.
If adopted by larger health care systems, this method should result in considerable savings. Other studies in different health care settings are needed before this method can be recommended on a wider basis.