Characteristics Influence Patients' Adherence to Medical Treatment

'IR1CAL Physicians' Characteristics Influence Patients' Adherence to Medical Treatment: Results From the Medical Outcomes Study

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M. Robin DiMatteo, Cathy Donald Sherbourne, Ron D. Hays, Lynn Ordway, Richard L. Kravitz, Elizabeth A. McGlynn, Sherrie Kaplan, and William H. Rogers The influence of physicians' attributes and practice style on patients' adherence to treatment was examined in a 2-year longitudinal study of 186 physicians and their diabetes, hypertension, and heart disease patients. A physician-level analysis was conducted, controlling for baseline patient adherence rates and for patient characteristics predictive of adherence in previous analyses. General adherence and adherence to medication, exercise, and diet recommendations were examined. Baseline adherence rates were associated with adherence rates 2 years later. Other predictors were physician job satisfaction (general adherence), number of patients seen per week (medication), scheduling a follow-up appointment (medication), tendency to answer patients' questions (exercise), number of tests ordered (diet), seriousness of illness (diet), physician specialty (medication, diet), and patient health distress (medication, exercise). Key words: physician characteristics, patient adherence, chronic-disease patients

Although failure to adhere to treatment recommendations can significantly limit the effectiveness of modern medical care, between 30% and 60% of all patients fail to take medications as they have been prescribed (Kaplan & Simon, 1990; Kruse & Weber, 1990; Luscher & Vetter, 1990). The problem of nonadherence (or noncompliance) is particularly acute when patients are required to take several medication doses per day (Cockburn, Gibberd, Reid, & Sanson-Fisher, 1987) or to carry out primary prevention efforts or significant changes in life-style (Brownell, Marlatt, Lichtenstein, & Wilson, 1986; United States Preventive Services Task Force, 1989). When long-term treatments for chronic disease have been prescribed, as many as 80% of all patients fail to carry out correctly at least one element of the management regimen (Rosenstock, 1988). A considerable amount of research has examined patient adherence to treatment recommendations, and several literature reviews exist on the topic (cf. Becker & Rosenstock, 1984; DiMatteo & DiNicola, 1982; Haynes, Taylor, & Sackett, 1979; Meichenbaum & Turk, 1987). Recently, investigations have begun to evaluate multivariate explanatory models (e.g., Janz & Becker, 1984; Sutton & Riser, 1990; Weerdt, Visser, Kok, & van der Veen, 1990). Most of this research has focused on patients' personal and demographic characteristics, patients' cognitions (including values, outcome expectancies, and efficacy expectancies), social influences (such as the support they receive and the norms to which they are subject), barriers (such as lack of resources and difficult treatment regimens) and past behavior. Insufficient attention has been paid, however, to the role of the health-care provider in promoting adherence to treatment (Koltun & Stone, 1986). Physicians' behavior (particularly communication style) has been cited by recent medical educators as a crucial element in

M. Robin DiMatteo, Cathy Donald Sherbourne, Ron D. Hays, Lynn Ordway, Richard L. Kravitz, Elizabeth A. McGlynn, Sherrie Kaplan, and William H. Rogers, RAND Corporation, Santa Monica, California. M. Robin DiMatteo is also at the University of California, Riverside; Ron D. Hays, Lynn Ordway, and Richard L. Kravitz are also at the University of California, Los Angeles; Sherrie Kaplan is also at the New England Medical Center, Boston. This research was supported by Agency for Health Care Policy and Research (AHCPR) Grant HS 06171 to Ron D. Hays and by the National Institute on Aging, the Robert Wood Johnson Foundation, the Henry J. Kaiser Family Foundation, the National Institute of Mental Health, the Pew Charitable Trusts, RAND, and the New England Medical Center. M. Robin DiMatteo's research on adherence to medical treatment has also been funded by the Research Network on Health and Behavior of the John D. and Catherine T. MacArthur Foundation. The views expressed are ours and do not necessarily represent those of the sponsors or of RAND. We gratefully acknowledge the following people who have contributed to the success of this study: Alan B. Cohen and Linda G. Aiken at the Robert Wood Johnson Foundation; Barbara H. Kehrer at the Henry J. Kaiser Family Foundation; Rebecca Rimel and Rosann Siegel at the Pew Charitable Trusts; Albert P. Williams and Mary Anderson at RAND; and especially Medical Outcomes Study staff and consultants, including Sandra H. Berry, Sandra Blau, M. Audrey Burnam, Maureen Carney, Sheldon Greenfield, Toshi Hayashi, Laural Hill, Adam Keller, Stephen Klein, Willard G. Manning, Judith Perlman, Anita L. Stewart, John E. Ware, and Kenneth Wells. We also thank the providers and patients who participated in this study, the secretarial expertise of Kim Wong and Jane-Ann Phillips, the support of Jean Carmody of AHCPR, and Lewin and Associates for their assistance in selecting the study sites. Correspondence concerning this article should be addressed to M. Robin DiMatteo, Department of Psychology, University of California, Riverside, California 92521-0426.

Health Psychology, 1993, Vol. 12, No. 2,93-102 Copyright 1993 by the American Psychological Association, Inc., and the Division of Health Psychology/0278-6133/93/$3.00

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patients' willingness and ability to follow treatment advice (Cassell, 1985a, 1985b). Patients have been more apt to fail to adhere to treatment recommendations when their physician has not provided clear explanations (Armstrong, Glanville, Bailey, & O'Keefe, 1990; Hall, Roter, & Katz, 1988; Korsch & Negrete, 1972; Ley & Spelman, 1965; Svarstad, 1976). Hall et al. (1988) found a trend toward greater adherence among patients of physicians who expressed positive verbal communications (e.g., reassurance, support, and encouragement) and refrained from negative verbal communications (e.g., anger, anxiety, and negative affect) during the medical visit. Physicians who reported doing more to promote patient adherence (frequency of engaging in compliance-enhancing behaviors) were found by Hall and Roter (1988) to ask more questions. The effect on adherence of time spent by physicians with their patients is equivocal, however, as some research reports a positive relationship (Beisecker & Beisecker, 1990; Fletcher, Pappius, & Harper, 1979) and other research reports a negative relationship (Freemon, Negrete, Davis, & Korsch, 1971). In addition, time spent with patients has been examined only cross-sectionally, and therefore it is unclear whether time is a cause or an effect of patient nonadherence. Little research has examined characteristics of the clinician that influence patient adherence to treatment. In a small sample of 28 medical residents, DiMatteo, Hays, and Prince (1986) found that physicians' sensitivity to (i.e., accuracy at decoding) voice-tone nonverbal communication was significantly related to their patients' adherence to scheduled appointments (r = .47). (Voice tone includes intonation, emphasis, pitch, and amplitude of speech and is classified as nonverbal because it involves characteristics of spoken communication apart from words.) The more sensitive physicians had fewer canceled and unrescheduled appointments than did those who were less sensitive to audio nonverbal cues. Health-care providers' job satisfaction is emerging as an important predictor of job performance. Weisman and Nathanson (1985) found that the job satisfaction of 344 family planning and community health nurses at 78 county health department family planning clinics in Maryland had a positive effect on patient satisfaction which, in turn, had a direct positive influence on patients' contraceptive use. A growing number of studies have linked low levels of physician job satisfaction with reduced work performance as measured by patient satisfaction and other measures of quality of care (Freeborn & Greenlick, 1973; Grol et al., 1985; Linn et al., 1985). McGIynn (1988) found that physicians' job satisfaction positively affected the satisfaction of their patients with the care they received even when visit time was limited. Physicians who were highly satisfied with the quality of the care that they delivered but who had shorter average visit lengths actually had higher mean patient satisfaction scores than did physicians whose ratings of satisfaction with the quality of care that they were able to deliver were low but who had longer average visit lengths. Thus, the role of physician job satisfaction in fostering patient adherence is an important avenue for study. The possible effects of physicians' age and gender on their patients' adherence to treatment are not yet clear. In some research, female physicians have been found to spend more time in the medical visit and to be more accepting of patients' feelings, more attentive during the visit, more open to the

psychosocial aspects of patient care, and more oriented toward preventive care than have male physicians (Maheux, Dufort, Beland, Jacques, & Levesque, 1990; Meeuwesen, Schaap, & van der Staak, 1991; Roter, Lipkin, & Korsgaard, 1991). In other research, however, female physicians viewed patient autonomy and initiative more negatively than did male physicians (Shye, Javetz, & Shuval, 1990). Although these factors might serve as mediators of patient adherence, the direct effects of physician gender on patient adherence have not been explored. The role of physician's age in patient's adherence to treatment is, at this point, equivocal. One group of investigators reported a positive association (Hurtado, Greenlick, & Columbo, 1973), whereas two other studies found a negative association (Cockburn et al., 1987; Hoogewerf, Hislop, Morrison, Burns, & Sizto, 1987) between physician's age and patient's treatment adherence. The purpose of the present study was to examine to what degree physicians' own personal characteristics and the characteristics of their practice affected patient adherence. To date, such research is rare because of the difficulties in collecting information about physicians and their practice and linking such data to the behavior of the physicians' own patients. Methodological limitations also plague adherence research, limiting the conclusions that might be drawn about the determinants of adherence (cf. Meichenbaum & Turk, 1987). Most studies, for example, have focused on narrow measures of adherence and its antecedents, have used limited samples of patients and providers (e.g., one geographic site and one practice), have used no control for case-mix differences, and have used cross-sectional designs. In the present study, we examined the role of physicians' personal and practice characteristics as predictors of their patients' adherence, and we avoided many of the methodological limitations of previous research by including multiple measures of adherence and its potential determinants, a large sample of providers and their patients, adequate control for case-mix differences, and a longitudinal design.

Method The data were from physicians and patients participating in the Medical Outcomes Study (MOS), an observational study of variations in physician practice style and patient outcomes. Details of the study design are provided in other publications (Rogers et al., 1992; Tarlov et al., 1989). Briefly, data for this analysis were obtained from patients visiting providers in five medical specialties (internal medicine, family practice, endocrinology, diabetology, and cardiology) practicing within three systems of care (health maintenance organizations [HMOs], large multispecialty groups [LMSGs], and solo practices) in three cities (Boston, Chicago, and Los Angeles). Physicians were sampled from lists obtained from the HMOs, LMSGs, and national professional associations; only those who were primarily engaged in patient care, who were board eligible, and who were between the ages of 31 and 55 were eligible. There was a participation rate of 85% for HMO and LMSG physicians and 54% for the solo practitioners. The final sample for this analysis, after eliminating providers who had missing data on any of the variables involved in the analysis, was 186 nonpsychiatric (non-mental health) physicians. The physicians enrolled in the MOS tended to be slightly younger that those in the general provider population and to have a slightly higher weekly patient load (but the same number of practice locations). There was a greater proportion of minorities and women, and


PHYSICIANS' CHARACTERISTICS providers were oversampled from the primary-care specialties (Rogers et al., 1992). The MOS involves both a cross-sectional study of patients visiting health-care providers and a longitudinal study of a subset of these patients with selected chronic conditions. For the cross-sectional component, patients were sampled from among literate, Englishspeaking adults visiting participating providers during a 9-day screening period in 1986. In all, 28,257 patients were approached, and 20,223 (71%) agreed to participate in the cross-sectional study. On the basis of physician reports, patients screened who appeared to have one or more of four chronic diseases (hypertension, diabetes, heart disease, and depression) constituted the sampling frame for the longitudinal panel (n = 8,040). We used a telephone interview to collect additional information and to ask eligible patients to enroll in the longitudinal panel. The enrolled sample included adult (18 and older) patients who (a) agreed to enroll in the study, (b) completed a screening questionnaire, and (c) reported symptoms of depressive illness or carried a physician's diagnosis of diabetes, hypertension, congestive heart failure, or myocardial infarction within the past year (n = 4,842). These patients all had an ongoing relationship with their physician, for no patients were enrolled in the longitudinal panel who indicated that the enrollment visit was their first visit with the physician. Compared with those who were ineligible or who refused to enroll, patients who enrolled in the MOS were younger, were somewhat better educated, had a higher income, and were more likely to be married and employed (Rogers et al., 1992). Of the 4,842 patients who enrolled, a panel of 2,546 patients was selected for further study. Patients were more likely to be selected for the final longitudinal panel of the MOS if they had current or lifetime depression as opposed to depressive symptoms only, had doctorcertified diabetes, were taking medication for their hypertension, and were elderly. We retained for the analyses presented in this article only patients who had a medical tracer, with or without depressive symptoms. The number of patients varied by the outcome variable with a maximum of 1,828. Among the 186 nonpsychiatric physicians, average characteristics for their patients were as follows: Average age was 60.1 years; 46% were men, and 54% were women; 18% were non-White, and 82% were White; 62% were married, and 38% were single or divorced. Average education was 13.2 years, and average mean family income was $23,159. Thirty-four percent of the patients had diabetes, 18% had heart disease, 72% had hypertension, and 16% had depressive symptoms in addition to one of the three medical tracer conditions. The total of these percentages exceeds 100 because some patients had more than one condition.

Measures Patients in the MOS longitudinal panel completed several selfreport questionnaires and a telephone interview. At the beginning of the study, they completed a screening questionnaire designed to gather information on chronic illness, sociodemographic information, and general health status. Shortly thereafter, these patients participated in a telephone interview. Then, approximately 3-4 months later, patients were administered the Patient Assessment Questionnaire— Baseline measure, and the patients completed a physical exam, which included a medical history questionnaire. At the end of Year 2 of the study, patients completed the Patient Assessment Questionnaire— Year 2. Physicians filled out both a screening and a background questionnaire at the beginning of the study. The questionnaire and telephone interview format were described in more detail in Tarlov et al. (1989). The patient and physician measures used in the present research (explained in more detail below) were collected at the following points of measurement in the MOS. (a) Patient Screening Self-Report: Comprised patient demographics and time spent in the MOS screening visit, (b) Tracer Condition Phone Interview: Patients were inter-

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viewed for the specific adherence measures detailed below, the adherence behaviors prescribed by the physician, (c) Patient Assessment Questionnaire—Baseline: Comprised patient's evaluation of physician's authoritative style, patient's physical functioning, patient's health distress, patient's avoidance coping, patient's social support, patient's overall satisfaction with care and satisfaction with access to and the interpersonal aspects of care, patient's general adherence at baseline, and patient's specific adherence at baseline, (d) Medical History Questionnaire—Baseline: Comprised clinical information to define disease severity, (e) Patient Assessment Questionnaire—Year Two: Comprised patient's general adherence at 2 years and three forms of patient's specific adherence at 2 years, (f) Physician Report Forms (screener form for each patient as well as a physician background questionnaire): Comprised practice characteristics—including number of practice locations, number of outpatient visits per week, hours per week seeing patients, number of tests used in the MOS screener visit, whether a definite follow-up appointment was made with the patient in the MOS screener visit, whether the physician made a referral to psychotherapy or requested a mental health consult for the screener-visit patient, whether the physician counseled patients regarding smoking cessation and weight loss during the screener visit, the physician's belief in the locus of responsibility for decision making, whether the physician usually answered all the questions a patient asked, the physician's self-description of the firmness of his or her interpersonal manner with patients, whether the physician ever discussed smoking cessation with patients, whether cost was considered when choosing treatments, whether the physician believed that patients should take responsibility for the care of their disease, whether the physician believed that doctors should maintain an authoritative position vis-a-vis patients, and whether the physician believed that caring and a personal approach to patients was important—and physician job satisfaction (global and five subscales). (g) Sampling Lists: Comprised physician practice type (solo, LMSG, or HMO) and specialty. Patient adherence. This study used self-report assessment of patient adherence instead of more expensive and cumbersome approaches such as collateral and physiological measures. The accuracy of selfreported adherence was maximized by maintaining confidentiality of the data and promoting a cooperative relationship between patients and the study team who collected the data. These procedures made it less likely that patients would be defensive and would deliberately distort their responses or that communication problems would otherwise render assessments inaccurate, as is particularly a concern when patient adherence reports are collected by health professionals themselves (Hays & DiMatteo, 1987). The MOS adherence measures are described below and are presented in greater detail elsewhere (DiMatteo, Hays, & Sherbourne, 1992; Sherbourne, Hays, Ordway, DiMatteo, & Kravitz, 1992). The General Adherence Scale assessed patients' general or typical tendencies to adhere to medical recommendations. These items were included on the baseline and 24-month patient assessment surveys: (a) I had a hard time doing what the doctor suggested I do; (b) I found it easy to do the things my doctor suggested I do; (c) I was unable to do what was necessary to follow my doctor's treatment plans; (d) I followed my doctor's suggestions exactly; and (e) Generally speaking, how often during the past 4 weeks were you able to do what the doctor told you? Response options for each item ranged from none of the time (1) to all of the time (6). Responses to the five items were averaged and then transformed linearly to a 0-100 distribution. Empirical analyses (factor analysis and multitrait scaling analysis) strongly supported the unidimensionality of the five items. Internal consistency reliability was 0.78 at baseline and 0.79 at the 2-year follow-up. The 2-year stability of the measure was 0.39 (DiMatteo et al., 1992). The specific adherence items assessed adherence to particular recommendations selected to be appropriate for patients with the MOS chronic conditions. The 15 items constituted two parallel lists,


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one of 15 specific treatment recommendations that could be made by the provider and the other of how often the patient had performed these actions. At the time of the tracer-condition phone interview, patients indicated which of the 15 potential adherence behaviors had been recommended to them by their physician during the past 4 weeks. Then, 3-4 months later (baseline) and 2 years later (follow-up), patients were asked on the Patient Assessment Questionnaire to indicate how frequently during the past 4 weeks they had adhered to each of the 15 behaviors. These 15 behaviors included taking medication, getting regular exercise, following a specific diet (low fat, weight loss, or low salt or a combination of the three), carrying out self-care activities (e.g., checking feet for minor bruises or carrying something with sugar in it), and using relaxation techniques and socializing more. Some activities were specific to a particular disease (e.g., carrying medical supplies for self-care for diabetes), whereas others were more general (e.g., exercising regularly). For this study, we derived three specific adherence subscales that measured the frequency that the patient (a) took all medications recommended, (b) exercised regularly, and (c) followed a special diet (weight loss, low fat, low salt, or a combination of the three). Possible responses on the scale ranged from none of the time (1) to all of the time (6). Each specific adherence subscale was scored only for patients who reported that they were told by their physician to carry out the behavior. Scores were transformed linearly to a 0-100 distribution. Two-year stability estimates for the subscales were .42 for medication, .44 for exercise, and .60 for diet. The measures of general and specific adherence were devised for the MOS, to address the complexities of adherence measurement. The general adherence measure focuses not only on the patient's reported success at following (perhaps several) recommendations in general but also on the ease with which he or she was able to do so. The measure provides an overall indication of the patient's difficulty and reported success at carrying out provider recommendations outside of a specific context. Factors that have a positive effect on general adherence may facilitate the patient's attempts to adhere. The specific adherence measures—including medication, exercise, and diet adherence—call for the patient's objective report of his or her actual behavior in response to a physician's recommendation. Content differences preclude a direct comparison of scores on the general and specific adherence measures. Previous research has documented noteworthy individual differences in adherence, depending on the specific behavior of concern. Patients who adhere to one recommendation do not necessarily adhere to another (Langlie, 1977; Mechanic, 1979). Provider variables. Characteristics of the provider included age, gender, ethnicity (White vs. non-White), practice type (solo, LMSG, or HMO), and specialty (internal medicine, family practice, endocrinology, diabetology, or cardiology). Provider practice characteristics included the number of different locations (excluding the emergency room) in which the physician conducted his or her outpatient professional practice, the physician's estimate of the average number of outpatient visits he or she had (in office, clinic, or other outpatient setting) in a typical week, and the physician's estimate of the average number of hours he or she spent in the office seeing patients in a typical week. Provider-style-of-practice variables included the physician's report of diagnostic test use (the number of different tests used during the MOS medical-screening visit for each patient), whether the physician made a follow-up appointment or telephone call with the patient during the medical-screening visit (scored 0 = no, 1 = yes; patient reported and averaged over patients), the total medical-screening visit time for the patient (patient estimated and averaged over patients), whether the physician made a mental health referral or asked for a mental health consult for any given screening-visit patient (scored 0 or 1 and averaged over patients), the physician's characterization of the firmness of his or her own personal manner with patients (3-point response scale), whether the physician reported that he or she

routinely discussed smoking cessation with patients (4-point response scale), whether the physician counseled medical-screening-visit patients in smoking cessation and weight loss (4-point response scale), the extent to which the physician considered cost when making treatment decisions (6-item scale; a internal consistency reliability = .70), the extent to which the physician believed that clients should make treatment decisions (4-item scale; a = .64), the extent to which the physician believed that physicians should maintain authority in patient care (4-item scale; a = .51), the physician's belief in the importance of caring and a personal approach to patients (6-item scale; a = .59), the extent to which the physician believed that responsibility for decision making in patient care belonged more to the doctor than to the patient (4-point response scale), and the physician's report of the extent to which he or she answered all of the questions a patient had regardless of how much time it took (4-point response scale). Also included as a provider-style-of-practice variable was a measure of the patient's perceptions of the physician's authoritativeness (consisting of the patient's response to 4 items—whether the doctor asked the patient to help decide among treatments, whether the doctor answered questions, whether the doctor made an effort to give the patient control, and whether the doctor asked the patient to take some of the responsibility for treatment—averaged over patients; a = 0.71). Professional job satisfaction was assessed using one global and five satisfaction subscales developed by McGlynn (1988). Physicians were asked to indicate their degree of satisfaction with the following: the quality of care they delivered (4 items; a internal consistency reliability = .71), their relationships with colleagues (2 items; a = .61), training and education (2 items; a = .60), finances (2 items; a = .67), personal time (2 items; ot = .94), and global professional job satisfaction (4 items; a = .87). The physicians ranked these items on a scale ranging from very dissatisfied to very satisfied. Patient characteristics for each physician were computed by averaging over all of the patients of that physician. These characteristics included patient age, tendency to use avoidance coping, physical functioning, health distress, and general satisfaction with medical care as well as satisfaction with two aspects of medical care (access and interpersonal care; Sherbourne et al., 1992). Seriousness of illness was assessed with a dichotomous indicator in which a 1 indicated that the patient had a serious illness and a 0 indicated that the patient had minor levels of the disease. On the basis of information from the Medical History Questionnaire and physical examination, clinical criteria were applied to define severity for each patient's disease condition. The approach to measuring disease severity in the MOS is described elsewhere (Kravitz et al., 1992). In addition, a composite measure of social support was computed for each patient. It included the perceived availability of emotional/informational, tangible, affectionate, and positive social interaction support (Sherbourne & Stewart, 1991); feelings of being loved and wanted, feelings that one had full love relationships, close relationships with friends and family (Stewart, Ware, Sherbourne, & Wells, 1992), and interpersonal functioning—that is, the communication, support, and togetherness of one's closest interpersonal relationship (Sherbourne & Kamberg, 1992). In the analysis, we also controlled for the prevalence of MOS tracer conditions (hypertension, heart disease, diabetes, and depressive symptoms if one of the other three tracers was also present). Although several more patient-level measures were available in the data set, we selected this subset as covariates because of their significant effect on patient adherence in the patient-level analyses of these data (see Sherbourne et al., 1992).

Statistical Procedures We evaluated the effects of the provider-level variables on adherence 2 years after baseline, controlling for adherence at baseline of the study. Separate models were run for the measures of general adher-

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PHYSICIANS' CHARACTERISTICS ence, medication adherence, exercise adherence, and diet adherence. We initially ran regression models with all of the covariates described previously. We then finalized the models by eliminating all covariates that were not significantly related to any of the outcome measures at thep < .05 level of significance. Thirty-four variables were retained. We then evaluated a completely saturated model for each outcome variable. We report those predictor variables that were significant at thep < .05 level.


Results Table 1 contains the means and standard deviations of the physician-level and averaged patient-level variables used in the saturated models. (Four variables involved controls for the tracer conditions as explained earlier, and one involved baseline adherence.) Providers were relatively young, predominantly male, White, in internal medicine, and practicing primarily in solo practices or HMOs. They tended to work in more than one practice location and varied widely in the number of patients they saw each week. They and their office staff spent approximately 23 min on average with patients in the MOS medical-screening visit. They were also very likely to make a follow-up screening visit with patients (93% of the time) and were very unlikely to make a mental health referral of their screening-visit patients. On average, they tended to express the opinion that the responsibility for decision making lay somewhat more with the patient than with the physician and tended toward answering many rather than few of their patients' questions. Table 1 also contains means and standard deviations of the four outcome measures at both baseline and 2-year follow-up. Patients' average general adherence improved slightly but significantly over the 2 years of the study. Exercise adherence did not change, and medication and diet adherence declined significantly over 2 years. In Appendix A, the zero-order correlations among the physician-level variables are presented; and in Appendix B, the intercorrelations of the four adherence measures at baseline and 2-year follow-up are presented. Although the relationships of the physician-level variables with the adherence variables are examined in multiple regression analyses later, some noteworthy zero-order intercorrelations among these variables were as follows: Younger physicians in this sample were more likely to be female and to specialize in family practice but less likely to specialize in cardiology. Female physicians were less likely to be in solo practice than male physicians and were more likely to work for HMOs. Female physicians were more likely to make a mental health referral or to obtain a mental health consultation in the screener visit. Non-White physicians were more likely to be in family practice and less likely to be in internal medicine. Non-White physicians also had more practice locations and saw more outpatients per week than did White physicians. Physicians in solo practice had their patients spend more time in the office during the MOS medical-screening visit and were more likely to make a definite follow-up appointment or arrange for a phone consultation. Physicians in solo practice reported that they were more likely to answer all of their patients' questions and were more satisfied overall with their jobs. Physicians in large, multispecialty practices had more practice locations and were less likely to make a follow-up

Table 1 Descriptive Statistics for Provider Variables Provider variable Demographics Years of age Gender Female Male Ethnicity White Practice type Solo practice Large multispecialty group HMO

Mor percentage

SD

40.1

6.7

18% 82% 82% 54% 17% 29%

Specialty

Internal medicine Family practice Endocrinology Diabetology Cardiology Practice characteristics No. practice locations No. outpt visits/wk. No. hrs/wk in office seeing patients Provider style of practice No. tests used in MOS screener visit Definite future follow-up appointment (0 = no; 1 = yes) Minutes spent in MOS screener visit (with physician, nurse, and other providers) Doctor's responsibility in decision making3 Doctor answers all patient questions'" Mental health consultation or referral in MOS screener visit Physician global job satisfaction Averaged patient variables Patient age Patient avoidance coping Patient physical functioning Patient health distress Patient social support Patient seriousness of illness (0 = no; 1 = yes) Patient satisfaction with access Patient satisfaction with interpersonal care Patient general adherence Baseline 2 years Patient medication adherence Baseline 2 years Patient exercise adherence Baseline 2 years Patient diet adherence Baseline 2 years

55% 25% 3% 4% 12% 1.5 71.2 28.6

0.7 34.4 9.5

0.11

0.06

0.93

0.15

23.1 1.68 2.68

9.6 0.5 0.6

0.02 74.8

0.1 18.6

60.1 2.1 70.6 17.5 0.2

8.4 0.4 14.1 10.8 0.5

0.28 73.3

0.2 7.9

73.8

7.9

74.2 76.8

11.7 13.1

92.3 89.1

15.7 18.3

40.7 41.5

19.7 21.2

66.3 61.6

19.2 20.8

Note, n = 186. HMO = health maintenance organization, outpt = outpatient, wk = week, hrs = hours, MOS = Medical Outcomes Study. On average, patients' self-reported general adherence improved significantly over 2 years,