Usual Source of Care in Preventive Service Use: A Regular Doctor versus a Regular Site

It has been well established that continuity of care is an important component of the quality of medical care (Starfield 1992). Lack of a usual source of care not only interrupts continuity of care but also imposes a significant barrier to receiving medical treatment. Having a usual source care is similar to having health insurance in the sense that both facilitate timely and adequate receipt of needed medical care (Baker, Stevens and Brook 1994; Chen and Lyttle 1987; Davis and Rowland 1983; Donelan et al. 1996; Rask et al. 1994; Robert Wood Johnson Foundation 1983; Saver and Peterfreund 1993; Weissman and Epstein 1993). In the Andersen–Aday behavioral model, both are considered enabling factors. Because both lack of a usual source of care and lack of insurance hinder care-seeking, Sox et al. (1998) attempted to compare the power of having a regular physician and having insurance in predicting individuals' access to health services. They concluded that, compared to having health insurance, having a regular physician was a stronger and more consistent predictor of patients' delay in seeking care, having no physician visits, and having no emergency department visits. The function of a usual source of care has been extensively discussed in the health services, public health, and medical literature. Age, gender, race, ethnicity, income, education, insurance status, and health status were found to be common correlates of having a regular source of care (Hayward et al. 1991; Hayward et al. 1988; Merzel 2000; Newacheck; Pearl et al. 1998; Newacheck, Stoddard et al. 1998; Rask et al. 1994; Schur, Albers, Berk 1995; Shi 1999; Weinick and Drilea 1998; Zuvekas and Weinick 1999). Having a usual source of care was demonstrated to be positively correlated with an individual's general access to the health care system (Weissman et al. 1991), improvement of patients' satisfaction with medical care (Hurley, Gage and Freund 1991), a decrease in the use of the emergency department (Newschaffer et al. 1999), a reduction in the likelihood of hospital admission (Weiss and Blustein 1996), and promotion of proper use of medication (Smith and Kirking 1999). In addition to improving access and utilization of medical care, having a usual source of care can facilitate the use of clinical prevention services in the population. It appears that adequate clinical prevention, such as immunization and cancer screening, can be better achieved through a usual source of care because the care provider has a more comprehensive understanding of a patient's health needs. Specifically, empirical evidence found that individuals with a usual source of care were more likely to receive timely immunizations (Flocke, Stange, Zyzanski 1998; Frank et al. 1995; Mark and Paramore 1996) and that women who had a usual source of care were more likely to receive breast and cervical cancer screening (Bindman et al. 1996; Ettner 1996; Kagawa-Singer and Pourat 2000; O'Malley et al. 1997; Zambrana et al. 1999). In addition, one study demonstrated that having a usual source of care promoted healthier behaviors, such as exercise and quitting smoking (Ettner 1999). Although many studies have investigated the effect of having a usual source of care on an individual's care-seeking behavior, most do not distinguish between having a regular doctor and having a regular site. Because of the positive association between having a regular doctor and improved access to care (Alpert et al. 1970; Becker, Drachman, and Kirscht 1974; Dietrich and Marton 1982; Starfield 1992), patients' preferences to see their usual physicians were included as one of the four domains in the Components of Primary Care Instrument (Flocke 1997). In two earlier studies comparing the effects of having a regular site and having a regular doctor (Marcus and Stone 1984; Scitovsky, Benham and McCall 1979), it was found that having a regular doctor resulted in a higher frequency of physician visits relative to having a regular site. One study pointed out that there was significant heterogeneity across different types of usual source of care (Lambrew et al. 1996). Individuals who had a regular doctor had a different care-seeking pattern from those who had a site as their regular source of care. Also, they found that the comparative advantage of having a regular doctor over having a regular site was diminished when nonmainstream sites (emergency rooms, outpatient departments, and family health centers) were excluded from the analysis. Another study found that the contribution of a regular doctor to consumers' perception of access was marginal when optimal primary care was provided at a site (Stewart et al. 1997). The notion that continuity and adequacy of care are improved by having a usual source of care may have different implications in different types of health services. In particular, from a patient's perspective, prevention is more voluntary (i.e., a matter of choice) than acute care. Having a usual source of care, in concept, can facilitate such planning. Although it is known that having a usual source of care improves access to preventive services, as discussed, whether a regular doctor contributes more than a regular site to the improvement of access to preventive services is yet to be explored. To further our understanding of the role of a usual source of care in ensuring that adequate and continuous prevention can be provided to the population, this study examined the relative effectiveness of having a regular doctor as compared to a regular site on individuals' use of various preventive services. Following Ettner (1996; 1999) and Kuder and Levitz (1985), in which the endogeneity of having a usual source of care was controlled for, this study answered the following questions: Does having a regular doctor have a greater impact on a patient's receipt of preventive services than having a regular site? In what preventive services do we observe the comparative advantage of having a regular doctor over having a regular site?