Nonresponse Bias in Estimates From the 2012 National Ambulatory Medical Care Survey.

BACKGROUND: The National Ambulatory Medical Care Survey (NAMCS) is an annual, nationally representative sample survey of physicians and of visits to physicians. Two major changes were made to the 2012 NAMCS to support reliable state estimates. The sampling design changed from an area sample to a fivefold-larger list sample of physicians stratified by the nine U.S. Census Bureau divisions and 34 states. At the same time, the data collection mode changed from paper forms to laptop-assisted data collection and from physician or office staff abstraction of medical records to predominantly Census interviewer abstraction using automated Patient Record Forms (PRFs). OBJECTIVES: This report presents an analysis of potential nonresponse bias in 2012 NAMCS estimates of physicians and visits to physicians. This analysis used two sets of physician-based estimates: one measuring the completion of the physician induction interview and another based on completing any PRF. Evaluation of visit response was measured by the percentage of expected PRFs completed. For each type of physician estimate, response was evaluated by (a) comparing percent distributions of respondents and nonrespondents by physician characteristics available for all in-scope sample physicians, (b) comparing response rates by physician characteristics with the national response rate, and (c) analyzing nonresponse bias after adjustments for nonresponse were applied in survey weights. For visit estimates, response was evaluated by (a) comparing the percent distributions of expected visits and completed visits, (b) comparing visit response rates by physician characteristics with the national visit response rate, and (c) analyzing visit-level nonresponse bias after adjustments for nonresponse were applied in visit survey weights. Finally, potential bias in the two physician-level estimates was computed by comparing them with those from an external survey.

Characteristics of Physician Office Visits for Obesity by Adults Aged 20 and Over: United States, 2012.

In 2011­2014, current asthma prevalence was higher among adults with obesity compared with adults in lower weight categories. This pattern was consistent across most demographic subgroups, except among men, for whom no statistically significant difference in current asthma prevalence by weight status was observed. Other epidemiologic studies of asthma prevalence have shown conflicting results about whether obesity is a risk factor for asthma among males. By race and Hispanic origin, current asthma prevalence was highest among adults with obesity for all groups. Patterns differed slightly among groups. For non-Hispanic black and Hispanic adults, prevalence for those with obesity was higher than for those in the normal weight and overweight categories. For non-Hispanic white adults, there was no signficant difference in asthma prevalence between the obese and overweight categories. For all age groups, current asthma prevalence was highest among adults with obesity, and there was no significant difference in asthma prevalence between those in the normal weight and overweight categories. There was an increasing trend in asthma prevalence as weight increased that was observed most clearly in the 60 and over age group. From 2001 to 2014, there was an increasing trend in current asthma prevalence among adults overall and among overweight adults. However, no significant trend was observed among adults in other weight categories. Findings from an American Thoracic Society workshop on obesity and asthma concluded that obesity is a major risk factor for asthma, and that obesity-related asthma is likely different from other types of asthma (e.g., allergic, occupational, exercise-induced, nocturnal, aspirin-sensitive, and severe asthma).

Variation in Physician Office Visit Rates by Patient Characteristics and State, 2012.

In 2012, 74% of children and adults with a usual place to visit listed a doctor's office as their usual place for care (1,2). This report examines the rate of physician office visits by patient age, sex, and state. Visits by adults with private insurance as their expected source of payment were also examined. Estimates are based on the 2012 National Ambulatory Medical Care Survey (NAMCS), a nationally representative survey of physician office visits. State estimates for the 34 most populous states are available for the first time. State refers to the location of the physician office visit.

Trends in emergency department visits for ischemic stroke and transient ischemic attack: United States, 2001-2011.

Stroke is the fifth leading cause of death in the United States. About 87% of all strokes are ischemic strokes. Transient ischemic attacks (TIAs) cause similar symptoms, but the blockage of blood flow to the brain is temporary. However, about one-third of people who have a TIA will have a stroke within 1 year (3). Emergency departments play a critical role in the diagnosis and management of ischemic stroke and TIA. The evaluation of these conditions in the emergency department is similar, so they are combined for this analysis. This report presents recent trends in visits to emergency departments for ischemic stroke or TIA.

Age differences in visits to office-based physicians by patients with diabetes: United States, 2010.

KEY FINDINGS: Data from the National Ambulatory Medical Care Survey. Office-based physician visits by patients with diabetes increased 20%, from 94.4 million in 2005 to 113.3 million in 2010, but the rate did not change between 2005 and 2010. The visit rate for diabetes increased with age and averaged 1,380 visits per 1,000 persons aged 65 and over in 2010. A majority of visits made by patients with diabetes (87%) were by those with multiple chronic conditions, and the number of chronic conditions increased with advancing age. Medications were prescribed or continued at a majority of visits (85%) made by patients with diabetes, with the number of medications prescribed or continued increasing as age increased. Diabetes is a chronic condition which affects nearly 29 million Americans and is a major cause of other chronic conditions, including heart disease, eye disease, and stroke (1). Diabetes was the seventh leading U.S. cause of death in 2009 and 2010 (2,3). Management of diabetes costs nearly $245 billion annually, and patients with diabetes have medical expenditures approximately 2.3 times higher than those for patients without diabetes (4). This data brief shows the trend from 2005 through 2010 for visits to office-based physicians by patients with diabetes, and describes age differences in the utilization of health care by patients with diabetes in 2010.

Pulmonary hypertension surveillance: United States, 2001 to 2010.

Pulmonary hypertension (PH) is an uncommon but progressive condition, and much of what we know about it comes from specialized disease registries. With expanding research into the diagnosis and treatment of PH, it is important to provide updated surveillance on the impact of this disease on hospitalizations and mortality. This study, which builds on previous PH surveillance of mortality and hospitalization, analyzed mortality data from the National Vital Statistics System and data from the National Hospital Discharge Survey between 2001 and 2010. PH deaths were identified using International Classification of Diseases, Tenth Revision codes I27.0, I27.2, I27.8, or I27.9 as any contributing cause of death on the death certificate. Hospital discharges associated with PH were identified using International Classification of Diseases, Ninth Revision, Clinical Modification codes 416.0, 416.8, or 416.9 as one of up to seven listed medical diagnoses. The decline in death rates associated with PH among men from 1980 to 2005 has reversed and now shows a significant increasing trend. Similarly, the death rates for women with PH have continued to increase significantly during the past decade. PH-associated mortality rates for those aged 85 years and older have accelerated compared with rates for younger age groups. There have been significant declines in PH-associated mortality rates for those with pulmonary embolism and emphysema. Rates of hospitalization for PH have increased significantly for both men and women during the past decade; for those aged 85 years and older, hospitalization rates have nearly doubled. Continued surveillance helps us understand and address the evolving trends in hospitalization and mortality associated with PH and PH-associated conditions, especially regarding sex, age, and race/ethnicity disparities.