FAQs (Data Related) Measuring Impact
- What are the best ways to measure the impact of arthritis?
- Can the BRFSS be used to measure effectiveness of state arthritis program interventions?
- Can sub-state-level BRFSS data be obtained?
In addition to prevalence and cost (discussed in the cost analysis FAQ section) there are several ways to measure the impact of arthritis in a state.
- Arthritis-attributable activity limitation. An important impact measure appears in the Arthritis Burden Questions of the BRFSS core. The question is: “Are you now limited in any way in any of your usual activities because of arthritis or joint symptoms?” The question is asked of all adult respondents. This question is also in the NHIS.
- Arthritis-attributable work limitation. One measure of arthritis impact on work appears in the Arthritis Burden Questions of the 2003 BRFSS core. This question also appeared in the 2009, 2011, and 2013 BRFSS core as part of the Arthritis Burden Questions. “In this next question we are referring to work for pay. Do arthritis or joint symptoms now affect whether you work, the type of work you do or the amount of work you do?” The question was only asked of respondents 18–64, the traditional working age population, in 2003; since then, the question has been asked of all respondents with arthritis age 18 or older, reflecting that people are staying in the workforce longer. The question is next expected to appear on BRFSS in 2015.
- Severity. States that collected data using the optional BRFSS Arthritis Management Module can select people with arthritis who report activity limitation and then use the first question on the Arthritis Management Module to judge severity: “Thinking about your arthritis or joint symptoms, which of the following best describes you today? I can do everything I’d like to do. I can do most things I would like to do. I can do some things I would like to do, or I can hardly do anything I would like to do.”
- Health-related, quality-of-life (HRQOL) measures. Health-related, quality-of-life (HRQOL) measures. The BRFSS has four questions on health-related quality of life. The first is on self-rated general health (excellent, very good, good, fair, poor). The other three questions cover the estimated number of days in the past month the respondent had a) poor physical health, b) poor mental health, and c) how many days poor physical or mental health kept them from their usual activities. Since the arthritis program’s goal is to improve the quality of life for persons with arthritis, these HRQOL measures are highly relevant. Improvement of these measures over time ( e.g., fewer poor physical health days on average) in the population of persons with arthritis would suggest that we are moving in the right direction.
The impact of arthritis can also be measured using national-level health care data to examine the impact of arthritis on hospitals, ambulatory care, and mortality. CDC does not recommend exploring hospital discharge, ambulatory care, or mortality data at the state level unless there is direct program relevance.
This is unlikely at present. BRFSS estimates provide useful statewide baseline data. State and partner interventions for arthritis now reach only a small proportion of the population in any state. For example, if BRFSS samples 2,000–3,000 people in a state, typically 21% of them will have doctor-diagnosed arthritis (500 to 700 people). The likelihood that your intervention reached any one of them will be small. When your program has grown very large and reaches many people with arthritis in the state, BRFSS may be able to help measure reach.
If you conducted a targeted intervention in a geographically defined area (e.g., city or county), and you collected a sufficient sample size of respondents in that area, you might be able to use the BRFSS or a telephone survey to evaluate the effort. For example, if you’re doing a health communications campaign, you might be able to use the BRFSS or a telephone survey to measure impact by working with your state BRFSS coordinator to target and over sample that particular area. The CDC Arthritis Epidemiology staff would be happy to consult with states interested in doing this.
The BRFSS produces estimates for large metropolitan/micropolitan statistical areas (MMSAs) with at least 500 respondents, although some of these cross state lines. These are from the SMART (Selected Metropolitan/Micropolitan Area Risk Trends) project (http://apps.nccd.cdc.gov/brfss-smart/index.asp, click on Local Area Health Risk data). Limited data for arthritis in these MMSA areas can be found using the category "arthritis". For non-MMSA areas, it would take at least 2 or 3 years of pooled BRFSS data to get a sufficient sample size to produce regional estimates. BRFSS recommends not making estimates for areas with fewer than 50 respondents.
The BRFSS web site can produce a map of state and local arthritis prevalence at http://apps.nccd.cdc.gov/gisbrfss/default.aspx.