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To assess primary care physicians’ (PCPs) knowledge of energy balance related guidelines and the association with sociodemographic characteristics and clinical care practices.
As part of the 2008 U.S. nationally representative National Survey of Energy Balance Related Care among Primary Care Physicians (EB-PCP), 1,776 PCPs from four specialties who treated adults (n=1,060) or children and adolescents (n=716) completed surveys on sociodemographic information, knowledge of energy balance guidelines, and clinical care practices.
EB-PCP response rate was 64.5%. For PCPs treating children, knowledge of guidelines for healthy BMI percentile, physical activity, and fruit and vegetables intake was 36.5%, 27.0%, and 62.9%, respectively. For PCPs treating adults, knowledge of guidelines for overweight, obesity, physical activity, and fruit and vegetables intake was 81.4%, 81.3%, 70.9%, and 63.5%, respectively. Generally, younger, female physicians were more likely to exhibit correct knowledge. Knowledge of weight-related guidelines was associated with assessment of body mass index (BMI) and use of BMI-for-age growth charts.
Knowledge of energy balance guidelines among PCPs treating children is low, among PCPs treating adults it appeared high for overweight and obesity-related clinical guidelines and moderate for physical activity and diet, and was mostly unrelated to clinical practices among all PCPs.
Obesity represents a significant public health concern. Possible solutions include the role of primary care physicians (PCPs) in promoting healthy diet, physical activity, and weight status among their patients. Patients regard their PCP as an important source of information related to nutrition [Tillotsen 2006], physical activity [Calfas et al, 1996], and weight [Galuska 1999]. Recent data from the National Survey of Energy Balance Related Care among Primary Care Physicians (EB-PCP), suggest that PCPs do not consistently assess, counsel, and follow-up with patients on their diet, physical activity and weight control (energy balance) practices, whether they treat children [Huang et al, 2011] or adults [Smith et al, 2011]. Knowledge deficits represent an important barrier to provision of weight-related care [Vetter et al, 2008]. The purpose of this study is to assess PCPs’ knowledge of physical activity-, diet-, and weight-related guidelines and their association with sociodemographic characteristics and energy balance-related clinical care practices.
Between March and September, 2008, 3,145 participants in the EB-PCP, a nationally representative survey of actively practicing PCPs in the U.S. received a questionnaire and 2,027 surveys were returned. The subject sample was obtained from the American Medical Association’s Physician Masterfile [AMA, 2010]. We excluded 251 surveys due to missing data for a final of 1,776 surveys (1,060 PCPs treating adults and 716 treating children) across four specialties (Internal Medicine (n=342), Obstetrics and Gynecology (OB/GYN, n=379), Family Practice (n=666), and Pediatrics (n=389). More details on sampling methodology are described elsewhere [Smith et al, 2011; Huang et al, 2011].
Two EB-PCP versions, one for PCPs treating children (ages 2–17 years) and one for PCPs treating adults (≥18 years), were used. (See: National Cancer Institute website http://www.outcomes.cancer.gov/surveys/energy/phys_pract_q_child.pdf and http://www.outcomes.cancer.gov/surveys/energy/phys_pract_q_adult.pdf). Since the EB-PCP was fielded prior to the 2008 guidelines [USDHHS, 2008], correct responses for physical activity included 30 minutes of moderate intensity physical activity on most days of the week for adults [Pate et al, 1995] and 60 minutes for children [Corbin and Pangrazi, 2004]. Fruit and vegetables intake linked to daily caloric intake [USDHHS, 2005] and daily intake of ≥5 fruits and vegetables [Pivonka et al, 2011] were both considered correct.
For PCPs treating adults, analyzed responses related to 1) overweight and obesity (BMI criteria), 2) number of servings of fruit and vegetables per day, 3) number of moderate intensity physical activity days per week (most days of the week), 4) all guidelines simultaneously correct. The same applied to PCPs treating children, except only healthy BMI percentile responses were considered.
Sociodemographic characteristics, including age, race, ethnicity, sex, and patient population treated were obtained from the EB-PCP. Specialty and census region were obtained from the AMA [AMA, 2010].
PCP energy balance-related clinical practices considered patients with an unhealthy diet, insufficient activity, or overweight status. PCPs were asked how often they: 1) provide general counseling; 2) provide specific guidance on diet, physical activity, or weight control; 3) refer to further evaluation or management; 4) systematically track/follow patients over time; and 5) assess BMI in adults or BMI, weight-for-age, stature-for-age, or BMI-for-age in children.
Sample weights compensated for differential selection probabilities, including oversampling of family practice physicians, non-response, and under-coverage of the target population. For variance estimation, we generated replicate weights using the Jackknife replication method [Wolter, 1985] and used SAS-callable SUDAAN (version 10.0 [Research Triangle Institute, 2008] for analyses. Chi-square tests were conducted to test differences between PCP knowledge and characteristics.
Binary logistic regression analyses were used to examine the relationships between PCP sociodemographic variables and knowledge. Analyses were stratified by patient population (child vs. adult). To examine associations between PCPs’ knowledge and clinical practices, we used multivariate ordinal logistical regression models and computed the likelihood of each care practice as the predicted probabilities from the corresponding logistic regression model. Covariates included in the final models were PCPs’ specialty, age, sex, race/ethnicity, and region. All alpha values were set at .05.
The EB-PCP response rate was 64.5%. For PCPs treating children, knowledge of guidelines for healthy BMI percentile, physical activity, fruit and vegetables, and all guidelines simultaneously was 36.5%, 27.0%, 62.9%, and 10.6%, respectively. For PCPs treating adults, knowledge of guidelines for overweight, obesity, physical activity, fruit and vegetables, and all guidelines simultaneously was 81.4%, 81.3%, 70.9%, 63.5%, and 40.6%, respectively. [Data shown in Appendix A]
Table 1 shows, among PCPs treating children, compared to other family practice physicians, pediatricians were more likely to report correct knowledge about healthy BMI percentile, fruit and vegetables intake, physical activity, and simultaneously meeting all guidelines. Female PCPs were more likely than male PCPs to report correct knowledge for healthy BMI percentile guidelines and physical activity guidelines.
Among PCPs treating adults (Table 1), compared to PCPs under 40 years old, older PCPs (≥50 years), were less likely to report correct knowledge about weight-related guidelines, fruit and vegetables intake, and all guidelines simultaneously. Compared to males, female PCPs reported higher levels of knowledge in relation to all guidelines.
Table 2 (multivariate analyses), indicates that among PCPs treating children with knowledge of healthy BMI percentile guidelines, fruit and vegetables intake, and all guidelines simultaneously, likelihood to assess BMI was higher. Knowledge of physical activity guidelines increased the likelihood to refer patients for further evaluation and management and to systematically track patients over time.
Among PCPs treating adults (Table 2), knowledge of overweight guidelines was associated with an increased likelihood to provide general counseling, guidance on diet, and assess BMI. A higher likelihood to assess BMI was associated with knowledge of obesity guidelines and all guidelines simultaneously. Knowledge of fruit and vegetables intake, as well as all guidelines simultaneously, was associated with a lower likelihood to provide guidance for weight control practices and the systematic tracking and follow-up of patients over time.
Weight-related clinical guidelines were first published over a decade ago [NIH 1998] and obesity is widely recognized as a clinical concern. However, physical activity guidance has not focused on PCPs and diet and physical activity-related guidelines have, until recently, not been supported by strong evidence of clinical effectiveness [Lin et al, 2010].
Knowledge of weight-related guidelines did correlate with more assessment of BMI and use of BMI-for-age growth charts. Clinical use of electronic medical records makes this practice simple and efficient. Pediatric HEDIS measures that call for measurement of BMI and physical activity and nutrition counseling are important to improve clinical care for weight-related concerns [NCQA 2009].
Limitations include the self-reported nature of the data and since fielding the EB-PCP, new guidelines have emerged thereby limiting applicability of findings. Finally, obesity represents a complex problem with causal factors that go far beyond the variables reported here.
Strengths include the nationally representative data, an almost 70% response rate, and baseline knowledge levels prior to new guideline releases provide opportunity to measure progress over time across PCP specialties.
Energy balance guidelines knowledge among PCPs treating children is low, whereas among PCPs treating adults it is relatively high for weight-related guidelines but moderate for physical activity and fruit and vegetables intake. Knowledge of all guidelines simultaneously is low for all PCPs. Knowledge appears largely unrelated to clinical care. Addressing gaps in knowledge is important; however, it is unlikely that knowledge improvement alone will be sufficient to generate improvements in clinical care.
Data collection for this survey was supported by the National Cancer Institute’s Contract No. N02-PC-61301. We would like to thank the members of the Department of Health and Human Services’ survey development team and outside consultants:
National Cancer Institute: Ashley Wilder Smith, Steven Clauser, Rachel Ballard-Barbash, Carrie Klabunde, Susan M. Krebs-Smith, Laurel Borowski, Emily Dowling, Gordon Willis, Richard Troiano, Audie Atienza, Tanya Agurs-Collins, Bill Davis
Eunice Kennedy Shriver National Institute of Child Health and Human Development: Terry Huang, Caroline Signore
National Institute of Diabetes and Digestive and Kidney Diseases: Mary Horlick, Myrlene Staten, Susan Yanovski
National Institutes of Health Office of Behavioral and Social Sciences Research: Deborah Olster
Centers for Disease Control and Prevention: Deborah Galuska, Laura Kettel Khan, Beth Tohill
National Heart, Lung, and Blood Institute: Barbara Wells, Karen Donato
Agency for Healthcare Research and Quality: Iris Mabry-Hernandez
Outside Consultants: Nico Pronk, Robert Kushner, Erica Frank, Jim Reschovsky, Gregory Pawlson
Disclaimer: The findings and conclusions of this report are those of the authors and do not necessarily represent the official position of the National Institutes of Health or the Centers for Disease Control and Prevention.
Conflict of Interest Statement: The authors of this paper declare there are no conflicts of interest.
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