Adult Obesity and Office-based Quality of Care in the United States


  • Jun Ma,

    Corresponding author
    1. Department of Health Services Research, Palo Alto Medical Foundation Research Institute, Palo Alto, California, USA
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  • Lan Xiao,

    1. Department of Health Services Research, Palo Alto Medical Foundation Research Institute, Palo Alto, California, USA
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  • Randall S. Stafford

    1. Program on Prevention Outcomes and Practices, Stanford Prevention Research Center, Stanford University School of Medicine, Stanford, California, USA
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Nationally representative data on the quality of care for obese patients in US-ambulatory care settings are limited. We conducted a cross-sectional analysis of the 2005 and 2006 National Ambulatory Medical Care Survey (NAMCS). We examined obesity screening, diagnosis, and counseling during adult visits and associations with patient and provider characteristics. We also assessed performance on 15 previously published ambulatory quality indicators for obese vs. normal/overweight patients. Nearly 50% (95% confidence interval (CI): 46–54%) of visits lacked complete height and weight data needed to screen for obesity using BMI. Of visits by patients with clinical obesity (BMI ≥30.0 kg/m2), 70% (66–74%) were not diagnosed and 63% (59–68%) received no counseling for diet, exercise, or weight reduction. The percentage of visits not being screened (48%), diagnosed (66%), or counseled (54%) for obesity was also notably higher than expected even for patients with known obesity comorbidities. Performance (defined as the percentage of applicable visits receiving appropriate care) on the quality indicators was suboptimal overall. In particular, performance was no better than 50% for eight quality indicators, which are all related to the prevention and treatment of obesity comorbidities, e.g., coronary artery disease, hypertension, hyperlipidemia, asthma, and depression. Performance did not differ by weight status for any of the 15 quality indicators; however, poorer performance was consistently associated with lack of height and weight measurements. In conclusion, many opportunities are missed for obesity screening and diagnosis, as well as for the prevention and treatment of obesity comorbidities, in office-based practices across the United States, regardless of patient and provider characteristics.


Obesity is an ever rising epidemic worldwide. In the United States, >60 million, or one in every three, adults are obese, as defined by BMI (calculated as weight in kilograms divided by height in meters squared) (1). Obesity is strongly associated with increased morbidity and mortality (2), as well as higher health-care utilization (3). Evidence-based clinical guidelines consistently recommend that clinicians screen all adult patients for obesity and offer intensive counseling about diet, exercise, and behavioral modification to promote sustained weight loss for obese adults (4,5). However, our previous work found that obesity was notably underdiagnosed (6,7) and lifestyle counseling was infrequently provided even among patients with physician-diagnosed obesity (8) in ambulatory care settings across the United States. Building on this research, we conducted this study to specifically examine patient and provider factors associated with a lack of obesity screening, diagnosis, and counseling for US adults seeking care in office-based private practices.

Research is growing on the association between obesity and the quality of care. Some studies reported fewer preventive care services among the obese (9,10,11,12,13), compared with persons of normal weight, whereas others demonstrated conflicting results (14,15). It is largely unknown whether and how obesity is associated with the quality of care for chronic and acute conditions. We examined the association of quality of ambulatory care with obesity by focusing on a set of previously developed quality indicators of chronic care, acute care, and preventive care in ambulatory settings (16). We hypothesized that, compared with their normal/overweight counterparts, obese patients would receive better quality of care on indicators for obesity-related disease or risk factor management whereas they would receive similar care on quality indicators for unrelated conditions.

Methods and Procedures

Data sources

The National Ambulatory Medical Care Survey (NAMCS) is administered annually since 1989 by the Ambulatory Care Statistics Branch of the National Center for Health Statistics (NCHS) of the Centers for Disease Control and Prevention. Complete descriptions of the survey and yearly public use data can be found at http:www.cdc.govnchsaboutmajorahcdahcd1.htm. The NCHS Institutional Review Board approved the protocols for the NAMCS, including a waiver of the requirement for informed consent of participating patients. The NAMCS has previously been validated against other national ambulatory care data (17,18).

The NAMCS collects information on utilization and provision of health care during patient visits to nonfederally funded, community, and office-based physician practices throughout the United States (19,20). It uses a three-stage stratified probability sampling design with sampling based on geographic location, office-based practices (stratified by specialty), and visits within office-based practices during randomly assigned reporting periods. The NCHS weights each patient visit to allow extrapolation to national estimates for all aspects of the survey. The visit weight accounts for selection probability, nonresponse adjustment, and other adjustments to reflect the universe of office-based patient visits in the United States. An independent sample of physicians is selected for each survey year.

The NCHS collects physician and practice information using the Physician Induction Interview Form at the start of the survey process. The characteristics included in this study were self-identified physician specialty, physician employment status, region of practice location, whether the practice was in a rural area, type of office setting, whether it was a solo practice, practice ownership, percent of practice's patient care revenue from managed care contracts, and whether the practice used an electronic health record. Information about individual physician demographic characteristics, such as age and gender, is not available in the NAMCS public use data.

Patient and clinical information is collected for each sample visit and is recorded on the NCHS standardized Patient Record Forms by participating physicians, office staff, or US Census Bureau representatives. The 2005 and 2006 Forms included patient information, particularly demographics and insurance status. Clinical characteristics included up to three reasons for the visit and eight medications, both coded according to the classification schemes developed at the NCHS (19,20,21). Listed medications included prescription and nonprescription medications that the physician prescribed or provided at or prior to the visit and that the physician expected the patient to continue taking. In addition, physician diagnoses were documented using (i) write-in spaces for up to three-visit diagnoses (later coded according to the International Classification of Diseases, Ninth Revision, Clinical Modification) and (ii) check boxes for a prespecified list of current medical problems, one of which was obesity, regardless of visit diagnoses.

We categorized visits according to the patient's risk for obesity-related disease complications and mortality. We used established clinical guidelines that were modified owing to limitations in our data source (5). Patients with any one of the following were classified as “high risk”: (i) coronary artery disease, (ii) diabetes mellitus, or (iii) other atherosclerotic diseases. Patients with any one of the following were classified as “moderate risk”: (i) men aged ≥45 years and women aged ≥55 years, (ii) hypertension, (iii) hyperlipidemia, (iv) cigarette smoking, (v) sleep apnea, (vi) osteoarthritis, or (vii) asthma. Finally, patients without any of those conditions were classified as “low risk.” Medical conditions were identified using either visit diagnoses or, if available, diagnostic check boxes. Patients whose encounter form did not indicate the presence of a condition were assumed not to have that condition.

Patient height and weight were collected, for the first time in 2005, and again in 2006. Survey instructions specified that the patient's height and weight be recorded using either measurements taken at the sample visit or, if not measured at the visit and the patient was ≥21 years, the most recent values in the patient's medical chart. BMI was computed during data processing by the NCHS staff for all patients with height and weight data, except for persons under the age of 2 and pregnant females.

Quality control was done using a two-way independent verification procedure for 10% of the sample records in each survey year. Coding error rates for various items ranged from 0.6 to 4.5% in 2005 and from 0.2 to 1.4% in 2006. Item nonresponse rates for most data elements were <5% in both years.

Data analysis

We performed a retrospective, cross-sectional analysis of ambulatory visits in the NAMCS from 2005 and 2006, the latest releases at the time of study. The study sample consisted of office-based visits by men and women ≥18 years (excluding pregnant women) to physicians with a specialty of general medicine, family medicine, internal medicine, and cardiovascular disease because many of the quality indicators concern the practice of primary care physicians and cardiovascular specialists.

We measured the number and percentage of ambulatory visits in which height and/or weight measurements were obtained. For patients who were obese by BMI, we measured the number and percentage of visits at which a physician diagnosis of obesity was recorded and counseling for diet, exercise, or weight reduction was provided or ordered. We also examined the associations of these measures with patient demographics, physician specialty, and practice characteristics.

Further, we examined a set of 15 indicators (Supplementary Data online) that measure the quality of ambulatory care during adult visits for management of chronic diseases (8 indicators), appropriate antibiotic use (2 indicators), and preventive counseling and screening services (5 indicators). Detailed criteria and methods for the construction of the quality indicators have been previously published (16,22). Briefly, the quality indicators were developed in accordance with the Institute of Medicine's criteria of clinical importance, scientific soundness, and feasibility for indicator selection as well as criteria specific to the limitations of the data source. The performance on quality indicators was the percentage of applicable visits receiving appropriate care (i.e., the higher the percentage the greater the performance). Visits meeting criteria for exclusion were removed from both the numerator and denominator for computing the percentage. Inclusions and exclusions were identified using the NAMCS reason for visit codes, medication codes, International Classification of Diseases, Ninth Revision, Clinical Modification codes, and diagnostic check boxes.

Statistical analysis

All analyses were performed with SAS statistical software, version 9.1.3 (SAS Institute, Cary, NC). The unit of analysis was the patient visit. We calculated standard errors for all results as recommended by the NCHS, which accounts for the sampling weights and complex multistage sampling design of the NAMCS (19,23). According to the NCHS, estimates with >30% relative standard error or based on <30 sample cases may be unreliable (19,23). Comparisons of 2005 and 2006 data suggested few differences on the main outcome measures. In accord with the NCHS analytical guidelines, we combined the data to obtain a larger sample size and, thus, more reliable estimates.

National estimates were generated using the SURVEYMEANS procedure for the number and percentage of patient visits, including 95% confidence intervals (CIs). χ2-Tests (PROC SURVEYFREQ) examined isolated associations between an outcome measure and individual explanatory variables. Explanatory variables that were at least nominally associated with an outcome measure (two-sided P < 0.10) were entered into a multiple logistic regression model (PROC SURVEYLOGISTIC) for that outcome. Adjusted odds ratios and associated Wald χ2 statistics from the logistic procedure were used to determine the significance of the independent association of an explanatory variable with the outcome measure after controlling for all other explanatory variables in the model. Statistical significance was set at two-sided P < 0.05.


Screening for obesity

In 2005 and 2006, American adults ≥18 years of age made 696 million visits (95% CI: 625–767 million) to office-based physicians in a specialty of primary care or cardiovascular disease. Of these visits, 50% (95% CI, 46–54%) had both height and weight measurements (hence BMI could be determined), 36% (95% CI, 32–40%) had a weight but not height measurement, and 13% (95% CI, 11–16%) had neither measurement. A very small percentage of total visits (0.9%) had a height but not weight measurement. Greater likelihood of lacking complete height and weight measurements to screen for obesity was independently associated with type of visit (OR, 1.6 (95% CI, 1.3–2.1) for treatment vs. preventive care visits) and region of practice location (1.7 (95% CI, 1.1–2.7) for the Northeast and 2.0 (95% CI, 1.2–3.4) for the West vs. Midwest) (Table 1).

Table 1.  Patient and provider characteristics and associations with height and weight measurements
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Obesity diagnosis and lifestyle counseling

Of the visits in which BMI was determined, 27% (95% CI, 26–29%) were made by normal weight patients, 31% (95% CI, 30–33%) by overweight patients, and 37% (95% CI, 35–40%) by obese patients. Only 30% (95% CI, 26–34%) of visits by patients who were obese by BMI had a physician-reported diagnosis of obesity. The likelihood of lacking obesity diagnosis for patients whose BMI was ≥30.0 was independently associated with patient gender (OR, 1.5 (95% CI, 1.2–2.0) for men vs. women) and region of practice location (1.8 (95% CI, 1.2–2.7) for the South vs. Midwest) (Table 2).

Table 2.  Patient and provider characteristics and associations with obesity diagnosis and lifestyle counseling for patients with a BMI of ≥30.0
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Counseling for diet, exercise, or weight reduction occurred in 37% (95% CI, 32–41%) of visits by patients who were obese by BMI and in 55% (95% CI, 47–62%) of visits by patients who also received a physician diagnosis of obesity (Table 2). The likelihood of patients with a BMI of ≥30.0 not receiving counseling was independently associated with risk of obesity comorbidities (OR, 1.6 (95% CI, 1.2–2.2) for moderate risk; 2.4 (95% CI, 1.7–3.5) for low risk vs. high risk), office type (2.9 (95% CI, 1.7–4.9) for free-standing clinics vs. private solo or group practices), and physician specialty (0.6 (95% CI, 0.4–0.9) for internal medicine vs. general/family medicine).

Performance of quality indicators

The performance was significantly >50% of applicable visits (the lower 95% CIs were >50%) for 7 of the 15 quality indicators, including 2 of the 8 quality indicators for medical management of common chronic diseases, both indicators for appropriate antibiotic use, and 3 of the 5 indicators for screening tests (Table 3). The two chronic disease management indicators whose performance exceeded 50% were use of antithrombotic agents in atrial fibrillation (67% (95% CI, 61–74%)) and aspirin use in coronary artery disease (54% (95% CI, 50–58%)). The performance was 70% (95% CI, 61–79%) for recommended antibiotic use for uncomplicated urinary tract infection and 71% (95% CI, 63–80%) for avoiding antibiotic use for uncomplicated upper respiratory tract infection. The performance was 93% (95% CI, 90–95%) of general medical examination visits for hypertension screening, 85% (95% CI, 81–89%) for avoiding routine electrocardiography, and 88% (95% CI, 82–94%) for avoiding routine urinalysis.

Table 3.  Indicator performance by obesity status
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Mean performance of the remaining six quality indicators for chronic disease management ranged between 31 and 51% of applicable visits. The indicators included angiotensin-converting enzyme inhibitor used for chronic heart failure, β-blocker used for coronary artery disease, diuretic used for hypertension, inhaled corticosteroid used for asthma, statin used for dyslipidemia, and pharmacotherapy or psychotherapy for depression. In addition, counseling about smoking cessation occurred in only 33% (95% CI, 25–41%) of annual general medical examination visits by current smokers. Routine complete blood count testing was avoided in 50% (95% CI, 39–61%) of all general medical examination visits.

Among visits with both height and weight measurements, no significant difference in quality was detected for any of the 15 indicators, including those for obesity-related disease and risk factor management, between the obese and nonobese (Table 3). Similar levels of quality also were observed for patient visits in which obesity status could not be determined due to lack of either (predominantly height) measurement, whereas poorer quality was noted for visits lacking both height and weight measurements.


Obesity is a complex chronic condition and health-care providers have an important role in identifying, preventing, and managing the disease (5). This study indicates that US office-based providers fail to prioritize obesity as a clinical issue. We found that providers often failed to obtain needed anthropometric patient data (height in particular) to screen for obesity and then failed to diagnose obesity even when data that were obtained identified the condition. In addition, our finding of low rates of counseling for diet, exercise, or weight reduction during visits by obese patients indicates that obesity is commonly undertreated. Rates of obesity screening, diagnosis, and counseling were comparably low across a wide array of patient and provider characteristics. Even among patients whose BMI was ≥30.0—definition of clinical obesity—and had significant comorbidities (e.g., coronary artery disease, diabetes, or other atherosclerotic disease)—only 34% (vs. 26% among obese patients without comorbidities) were diagnosed with obesity and 46% (vs. 26%) received counseling.

Obesity-related disease complications increase health-care costs, reduce quality of life, and shorten life expectancy (2,24), underscoring the importance of prevention and treatment of obesity. Even modest weight reductions (typically in the range of 5–10% of initial body weight)—as opposed to the large reductions necessary to achieve ideal or normal weight—significantly improve surrogate disease outcomes (25,26) and obesity-related morbidity (27,28). Current national guidelines recommend that, to promote modest, sustained weight loss for obese adults, clinicians offer intensive counseling about diet and exercise, as well as counseling about behavioral strategies to help patients acquire the skills, motivation, and support needed to change eating patterns and food preparation practices and to become physically active (4,5). The evidence remains unclear with regard to the efficacy of moderate- or low-intensity counseling together with behavioral interventions in inducing sustained weight loss for obese adults (4). The US Preventive Services Task Force defines intensity of counseling by the frequency of contact—an intervention is high intensity if it involves more than one person-to-person (individual or group) session per month for at least the first 3 months (4). Current antiobesity medications have significant side effects and data on their long-term (longer than 2 years) benefits or side effects are lacking (5). If prescribed, these medications should be used in conjunction with intensive counseling about diet, exercise, and behavioral modification (5). Finally, weight loss surgery is costly and should be reserved for patients with severe obesity who have at least one clinically significant comorbidity (5).

The results of this study rejected our hypothesis that obesity would be associated with higher performance on quality indicators for obesity-related disease or risk factor management. Instead, we found that obese patients received similar, although largely suboptimal, care as normal or overweight patients on all 15 ambulatory quality indicators. We noted, however, that poorer performance was consistently associated with lack of height and weight measurements, which occurred in 13% (95% CI, 11–16%) of total visits. This finding may be due to the minimal nature of visits during which neither height nor weight is measured. In addition, the lack of systems for measuring and documenting height and weight may be correlated with similar lack of systems that could facilitate higher ambulatory care quality.

Our finding that obesity is not generally associated with differential quality of ambulatory care may not be extrapolated to quality indicators not measured in this study. However, this finding is consistent with past reports (including our own) that once patients were in the exam room, patient characteristics, such as race, income, and insurance status, made little difference in the quality of care patients receive from their physicians (16,29). These findings are not a refutation of the substantial evidence of health disparities by race, ethnicity, and socioeconomic status (30) and the emerging evidence of disparities in the obese (9,10,11,12,13). Instead, they imply that these disparities do not arise primarily from unequal treatment in doctors' offices. Strategies to successfully reduce health disparities will need to address the underlying social, cultural, and economic issues faced by patients who are known to be affected by these disparities as they attempt to access the health-care system. Some studies have reported that obese persons may encounter considerable social, economic, and psychological barriers, including, but not limited to, higher premiums for health insurance, less income, other forms of societal discrimination, and poor self-perception (31,32,33,34). Further, obese individuals may be reluctant to see health-care professionals because of their concern about clinician attitudes toward their appearance, discomfort with medical procedures (especially those involving disrobing and manual manipulation of their bodies), or the nature of the interaction with a clinician in general (35,36).

Beyond the lack of association between obesity and quality, it is worth noting that the performance on most indicators was suboptimal. Room for improvement was substantial for at least 8 of the 15 quality indicators in that no >50% of applicable visits received appropriate care. These eight quality indicators are concentrated in the areas of chronic disease management and preventive services. In comparison with our previously published data on the same measures (16), improvements in quality since 2002 were modest. The 2007 National Healthcare Quality Report cites slower quality improvement between 2000 and 2005 compared to modest improvement between 1994 and 2000, with gaps continuing to be most substantial in chronic and preventive care (37). These data lend support to the assertion that continuing, meaningful quality improvement requires fundamental reforms of clinical care that will shift the emphasis from acute care to chronic and preventive care, e.g., through implementing a systems approach to patient-centered, collaborative care (38,39,40).

This study has several limitations that should be considered in interpreting its results. First, the NAMCS is a cross-sectional survey, and any statistically significant associations do not imply causation. We provided 95% CIs for all reported statistics to help gauge the size and precision of any observed differences in point estimates. The consistency of the findings in this study indicates their reliability; however, these findings need to be corroborated in future investigations. Second, our findings reflect the rates of obesity-related services and the performance of selected quality indicators in the general US office-based outpatient population only to the extent to which information was accurately reported and coded on the encounter forms. Both over- and under-reporting are possible, and the magnitude of bias is difficult to predict. On the one hand, because the NAMCS data are linked to patient visits rather than individual patients, sicker, more frequent users of outpatient care (e.g., obese patients with comorbidities requiring continuing medical care) may be oversampled, and the prevalence of medical conditions (e.g., patients diagnosed with obesity) and the provision and utilization of ambulatory health-care services (e.g., obese patients receiving lifestyle counseling) may be overestimated. On the other hand, the per-patient visit basis may be associated with a reduced likelihood of reporting or treatment for patients at any given visit who see physicians more often. Patients lacking diagnoses (e.g., obesity) or services (e.g., lifestyle counseling) at a particular visit may have received those diagnoses and services at another visit. Third, an additional potential limitation closely related to accuracy of the NAMCS data is the quality of height and weight measurements. The proportion of patients whose height and weight were measured at the time of the visit vs. those who had a historic height and weight is unknown and the accuracy of the measurements cannot be verified. Therefore, misclassification of individuals as obese based on height and weight data recorded in the NAMCS is possible.

Despite these limitations, the NAMCS is the best data source available to date that captures health-care services in office-based ambulatory care settings throughout the United States. The inclusion of height and weight measurements beginning in 2005 provides a unique opportunity for assessing obesity status and its association with the quality of ambulatory care in this nationally representative survey.

To conclude, the evidence is compelling that obesity is underappreciated in office-based physician practices across the United States. Many opportunities are missed for obesity screening and diagnosis, as well as for the prevention and treatment of obesity and related health risks, regardless of patient and provider characteristics. Quality is equally suboptimal on a number of measures, particularly those of chronic disease management and preventive counseling, for both normal/overweight and obese patients. These findings are not surprising given that the current primary care delivery model continues to lack the structure and organization needed to effectively prevent and manage obesity and many other chronic diseases (41). The health-care system's acute care orientation, structure of physician visits and reimbursement, and lack of a population health orientation contribute to the neglect of chronic and preventive care. Optimal health care for the growing numbers of Americans with chronic diseases requires both a change in the conceptualization of health-care models and in the implementation of health care itself (38,39,40).


Supplementary material is linked to the online version of the paper at http:www.nature.comoby


This research was supported by internal funding from the Palo Alto Medical Foundation Research Institute (Drs Ma and Xiao) and by National Institutes of Health funding (Dr Stafford, grant K24 HL086703). Previous funding (grant R01 HS11313) from the Agency for Healthcare Research and Quality, Rockville, Maryland, supported the development and evaluation of the quality indicators used in the present study. No sponsor or funding source had a role in the design or conduct of the study; collection, management, analysis, or interpretation of the data; or preparation, review, or approval of the manuscript.


The authors declared no conflict of interest.