Primary care physician turnover in HMOs.

OBJECTIVE: We assess whether physician turnover stems from incorrect physician expectations about the practice environment or from actual constraints or rewards in that environment. DATA SOURCES: Our primary data source contains information about individual HMOs' primary care physicians incentive mechanisms and general HMO characteristics. Our secondary data source is the area resource file (ARF), which contains countywide information about the HMOs' market areas, including physician characteristics, population characteristics, and other market characteristics. DATA COLLECTION: Our primary data source is from a nationwide survey of all HMOs in operation in 1987-1988, as reported to Interstudy. PRINCIPAL FINDINGS: We find that turnover is higher on the part of physicians whose HMO enrollment comprises a greater percentage of their total practice. Our results further indicate that physicians whose compensation is dependent on the behavior of a group of other physicians are more likely to leave the plan than those who bear the risk (and control it) more directly. On the other hand, turnover is increased by basing bonuses on individual productivity and by not sharing surpluses among a group. Market characteristics also are significant in explaining physician turnover in HMOs. CONCLUSIONS: It appears that physicians accurately forecast how they will react to individual financial risk, although they dislike restrictions imposed by HMOs.

Peripheral mechanisms of fatigue in muscles of normal and dystrophic mice.

We evaluated the contribution of different processes to fatigue of normal and dystrophic mouse muscles using an in vitro electromyography chamber. Fatigue was induced by repetitive nerve stimulation at 30 Hz for 0.5 s, every 2.5 s until tension decreased by about 50%. We monitored the compound nerve action potential (AP), compound muscle AP, and isometric tension responses to nerve stimulation, and compound muscle AP and tension responses to direct muscle stimulation. In normal mice, about 50% reduction in nerve-evoked tension occurred by 2.4 min in extensor digitorum longus (EDL), 4.8 min in diaphragm, and 9 min in soleus. Analysis of the responses revealed that the fatigue was caused by failure of more than one process in all muscles, and failure of nerve conduction did not contribute to fatigue in any muscle. Failure of neuromuscular transmission, muscle membrane excitation, and excitation-contraction (E-C) coupling and contractility accounted for 55, 45, and 0%, respectively, of the fatigue in EDL, for 21, 74, and 5% of the fatigue in diaphragm, and for 2, 54, and 44% of the fatigue in soleus. In dystrophic mice, while about 50% reduction in nerve-evoked tension occurred by 8.1 min in EDL and 5.6 min in diaphragm, only 29% reduction in tension occurred by 80 min in soleus. Failure of neuromuscular transmission, muscle membrane excitation, E-C coupling and contractility accounted for 22, 63 and 15% of the fatigue in EDL, for 21, 79, and 0% of the fatigue in diaphragm, and for 15, 59, and 26% of the fatigue in soleus. The proportion of slow-twitch oxidative fibers was more than normal in dystrophic EDL, but the same as normal in dystrophic diaphragm and soleus. The slower onset of fatigue was attributable to lesser failure of neuromuscular transmission in dystrophic EDL, and to lesser failure of E-C coupling and contractility in dystrophic soleus.

Managing physician incentives in managed care. The role of for-profit ownership.

The recent rapid growth of HMOs has resulted in a proliferation of contractual arrangements that offer financial incentives to induce primary care doctors to change the way they practice medicine. The impact of these incentives varies with the different incentives and with the environments in which the incentives are implemented. Although financial incentives exist in some form in the great majority of HMOs, there has been no detailed and valid information available on the way these physician incentives are managed or on the characteristics of the standard operating "climate" in which the incentives exist. This study was designed to measure a firm (organizational) characteristic hypothesized to be related to the firm's effort, ability, or desire to make financial incentives work strongly. The characteristic considered is whether the firm is a for-profit or a not-for-profit organization. The goal of this study was to provide a direct test of the relationship between HMO ownership type and the effectiveness of primary care physician incentives. Results of the study indicate that for-profit ownership does enhance the power (or the need) of management to offer effective rewards for parsimonious use of health care resources.

How do financial incentives affect physicians' clinical decisions and the financial performance of health maintenance organizations?

It has been suggested that the use of financial incentives by health maintenance organizations (HMOs) may change physicians' behavior toward individual patients. To test this hypothesis, we used a regression analysis of data from a survey of HMOs to examine the relation between the presence of financial incentives and two measures of the use of resources (the rate of hospitalization and the rate of visits for outpatient services) and one measure of the HMOs' financial viability (the achievement of break-even status). When we controlled for the effect of market-area variables, we found that some forms of compensation were significantly associated with these indicators of decision making by physicians. Among methods of paying physicians, the use of capitation or salaries was associated with a lower rate of hospitalization than the use of fee-for-service payment; physicians in for-profit HMOs and group-model HMOs also used the hospital less often. Placing physicians at financial risk as individuals and imposing penalties for deficits in the HMO's hospital fund beyond the loss of withheld funds were associated with fewer outpatient visits per enrollee, but a higher percentage of HMO patients in a physician's caseload was associated with more frequent visits. HMOs were more likely to break even if they were larger, older, had physicians who treated more HMO patients, and placed physicians at personal financial risk for the cost of outpatient tests; break-even status was also related to the type of HMO. We conclude that the use of some, but not all, financial incentives, as well as the type of HMO, does influence the behavior of physicians toward patients. It remains to be determined how these factors affect the quality of care.