BACKGROUND: Recent work has shown that rates of severe disability, measured by the inability to perform basic activities of daily living, have been rising in working age populations. At the same time, the prevalence of important chronic diseases has been rising, while others falling, among working age populations. Chronically ill individuals are more likely than others to have activity of daily living limitations.

OBJECTIVE: We examine the extent to which chronic disease trends can explain these disability trends. DATA: We use nationally representative survey data from the 1984-1996 National Interview Survey, which posed a consistent set of questions regarding limitations in activities of daily living over that period.

METHODS: We decompose trends in disability into 2 parts-1 part due to trends in the prevalence of chronic disease and the other due to trends in disability prevalence among those with chronic disease.

RESULTS:: Our primary findings are that for working age populations between 1984 and 1996: (1) disability prevalence fell dramatically among the nonchronically ill; (2) rising obesity prevalence explains about 40% of the rise in disability attributable to trends chronic illness; and (3) rising disability prevalence among the chronically ill explains about 60% of the rise in disability attributable to trends in chronic illness.

CONCLUSIONS: Disability prevention efforts in working age populations should focus on reductions in obesity prevalence and limiting disability among chronically ill populations. Given the rise in disability among these population subgroups, it is unclear whether further substantial declines in elderly disability can be expected.

Context: Without detailed evidence of their effectiveness, pedometers have recently become popular as a tool for motivating physical activity.

Objective: To evaluate the association of pedometer use with physical activity and health outcomes among outpatient adults.

Data Sources: English-language articles from MEDLINE, EMBASE, Sport Discus, PsychINFO, Cochrane Library, Thompson Scientific (formerly known as Thompson ISI), and ERIC (1966-2007); bibliographies of retrieved articles; and conference proceedings.

Study Selection: Studies were eligible for inclusion if they reported an assessment of pedometer use among adult outpatients, reported a change in steps per day, and included more than 5 participants.

Data Extraction and Data Synthesis: Two investigators independently abstracted data about the intervention; participants; number of steps per day; and presence or absence of obesity, diabetes, hypertension, or hyperlipidemia. Data were pooled using random-effects calculations, and meta-regression was performed.

Results: Our searches identified 2246 citations; 26 studies with a total of 2767 participants met inclusion criteria (8 randomized controlled trials [RCTs] and 18 observational studies). The participants' mean (SD) age was 49 (9) years and 85% were women. The mean intervention duration was 18 weeks. In the RCTs, pedometer users significantly increased their physical activity by 2491 steps per day more than control participants (95% confidence interval [CI], 1098-3885 steps per day, P .001). Among the observational studies, pedometer users significantly increased their physical activity by 2183 steps per day over baseline (95% CI, 1571-2796 steps per day, P .0001). Overall, pedometer users increased their physical activity by 26.9% over baseline. An important predictor of increased physical activity was having a step goal such as 10,000 steps per day (P = .001). When data from all studies were combined, pedometer users significantly decreased their body mass index by 0.38 (95% CI, 0.05-0.72; P = .03). This decrease was associated with older age (P = .001) and having a step goal (P = .04). Intervention participants significantly decreased their systolic blood pressure by 3.8 mm Hg (95% CI, 1.7-5.9 mm Hg, P .001). This decrease was associated with greater baseline systolic blood pressure (P = .009) and change in steps per day (P = .08).

Conclusions: The results suggest that the use of a pedometer is associated with significant increases in physical activity and significant decreases in body mass index and blood pressure. Whether these changes are durable over the long term is undetermined.

This issue of CHP/PCOR's Quarterly Update covers news from the Summer 2007 quarter and includes articles about:

• two reports on care coordination -- one on care coordination strategies in general, and a second on care coordination specifically for children with special health care needs;

• an international health section that features work done by undergraduates this summer (with mentorship and guidance from CHP/PCOR staff) on the GOBI initiative, as well as a summary of a the new Children's Project established by core faculty member Paul H. Wise;
• two Research in Brief selections -- one highlights the impact of pay for performance reimbursement structures on end-stage renal disease care, and the second examines the link between obesity and wages in Europe;
• a Medicare restructuring and refinancing piece that highlights the work of director and core faculty member Alan M. Garber, core faculty member Victor R. Fuchs, and colleagues;
• a piece on the effect of chronic illnesses such as obesity on disability trends in the near-elderly population;
• a Staff Spotlight feature on two CHP/PCOR research assistants.

Note to the reader:

The newsletter is fully-navigational. Any text that is surrounded by a dashed box is clickable and will allow the reader to navigate the newsletter more efficiently. The end of each article contains a special symbol (§) that, when clicked, will take the reader back to the table of contents. Please feel free to contact Amber Hsiao with any questions.

This issue of CHP/PCOR's Quarterly Update covers news from the Fall 2006 quarter and includes articles about:

• the effect of health insurance on obese individuals' behaviors, as well as possible approaches and policy questions with regards to the obesity epidemic;
• the state of disaster preparedness in the United States. Are we ready yet? Experts provided comments at a fall conference and presented data on the intricacies of the topic;
• the state of children's health -- two pieces provide broad coverage of international and U.S.-based news on current policies and debates surrounding children's health;
• the health services and policy research scholarly concentration within the School of Medicine, with a special profile piece from a third-year medical student; and
• two Research in Brief selections, a new feature that highlights recently-published CHP/PCOR research and how such research is informing health care practices and public perceptions.

There has been concern about the dramatic growth in obesity seen in developed countries. This paper advances the view that a neoclassical interpretation of weight growth that relies on changing incentives does surprisingly well in explaining the observed trends, without resorting to psychological, genetic, or addictive models.

Past research has identified social and environmental causes and correlates of behaviors thought to be associated with obesity and weight gain among children and adolescents. Much less research has documented the efficacy of interventions designed to manipulate those presumed causes and correlates. These latter efforts have been inhibited by the predominant biomedical and social science problem-oriented research paradigm, emphasizing reductionist approaches to understanding etiologic mechanisms of diseases and risk factors. The implications of this problem-oriented approach are responsible for leaving many of the most important applied research questions unanswered, and for slowing efforts to prevent obesity and improve individual and population health. An alternative, and complementary, solution-oriented research paradigm is proposed, emphasizing experimental research to identify the causes of improved health. This subtle conceptual shift has significant implications for phrasing research questions, generating hypotheses, designing research studies, and making research results more relevant to policy and practice. The solution-oriented research paradigm encourages research with more immediate relevance to human health and a shortened cycle of discovery from the laboratory to the patient and population. Finally, a "litmus test" for evaluating research studies is proposed, to maximize the efficiency of the research enterprise and contributions to the promotion of health and the prevention and treatment of disease. A research study should only be performed if (1) you know what you will conclude from each possible result (whether positive, negative, or null); and (2) the result may change how you would intervene to address a clinical, policy, or public health problem.

If rational individuals pay the full costs of their decisions about food intake and exercise, economists, policy makers, and public health officials should treat the obesity epidemic as a matter of indifference. In this paper, we show that, as long as insurance premiums are not risk rated for obesity, health insurance coverage systematically shields those covered from the full costs of physical inactivity and overeating. Since the obese consume significantly more medical resources than the non-obese, but pay the same health insurance premiums, they impose a negative externality on normal weight individuals in their insurance pool.

To estimate the size of this externality, we develop a model of weight loss and health insurance under two regimes——(1) underwriting on weight is allowed, and (2) underwriting on weight is not allowed. We show that under regime (1), there is no obesity externality. Under regime (2), where there is an obesity externality, all plan participants face inefficient incentives to undertake unpleasant dieting and exercise. These reduced incentives lead to inefficient increases in body weight, and reduced social welfare.

Using data on medical expenditures and body weight from the National Health and Interview Survey and the Medical Expenditure Panel Survey, we estimate that, in a health plan with a coinsurance rate of 17.5%, the obesity externality imposes a welfare cost of about $150 per capita. Our results also indicate that the welfare loss can be reduced by technological change that lowers the pecuniary and non-pecuniary costs of losing weight, and also by increasing the coinsurance rate.

This issue of CHP/PCOR's quarterly newsletter covers developments from the spring 2005 quarter. It includes articles about:

• research on HIV/AIDS in Russia -- presented in May at an international conference -- which shows that in order to contain the country's rapidly expanding HIV/AIDS epidemic, Russia must aggressively treat HIV-positive injection drug users;
• a CHP/PCOR-hosted discussion session with Edward Sondik, director of the National Center for Health Statistics;
• an ongoing CHP/PCOR study that examines older adults' preferences about health states in which they would need help with basic tasks like bathing or eating;
• a panel discussion on "International Responses to Infectious Diseases," led by CHP/PCOR at the Stanford Institute for International Studies' first annual conference, featuring the World Health Organization's chief of infectious diseases;
• a widely publicized study by CHP/PCOR researchers which found that obese workers are paid less than non-obese workers in similar jobs, but only when they have employer-sponsored health insurance -- a finding suggesting that the wage gap is due to obese workers' higher medical costs, rather than outright prejudice; and
• an update on the Center on Advancing Decision Making for Aging, including two new seed projects and a lecture given by economics and psychology professor George Loewenstein.