THURSDAY, April 28 (HealthDay News) -- A new study helps confirm what many Americans with arthritis may already know: the illness can greatly diminish quality of life.

Researchers analyzed data from 1 million adults who took part in the national Behavioral Risk Factor Surveillance System survey in 2003, 2005 and 2007. Poor or fair health was reported by 27 percent of respondents with arthritis compared to 12 percent of those without arthritis.

Compared to other adults, those with arthritis had a higher average number of physically unhealthy days per month (seven versus three), mentally unhealthy days (five versus three), total unhealthy days (10 versus five) and activity-limited days (four versus one), according to the report published online April 28 in the journal Arthritis Care & Research.

The study also found that people with arthritis-related limitations to normal activities had poorer health-related quality of life than those without such limitations.

Values for all five measures of health-related quality of life were two to three times worse in adults with arthritis compared to those who were arthritis-free. The five measures included: demographics (age, sex, ethnicity/race); social factors (employment status, education and income levels); health care factors (access and cost barriers to obtaining care); health behaviors (smoking, alcohol use, physical activity levels); and health conditions (diabetes, weight, high blood pressure).

Low family income, inability to work, being unable to afford care and having diabetes were all strongly associated with poor health-related quality of life, Sylvia Furner, of the School of Public Health at the University of Illinois at Chicago, and colleagues noted.

In addition, adults with arthritis who were physically active were less likely to report fair or poor health, the study authors pointed out.

"Given the projected high prevalence of arthritis in the U.S., interventions should address both physical and mental health," Furner concluded. "Increasing physical activity, reducing [co-existing disorders], and increasing access to health care could improve the quality of life for adults with arthritis," she explained in a journal news release.

About 50 million American adults have doctor-diagnosed arthritis and that number could climb to 67 million by 2030, according to the U.S. Centers for Disease Control and Prevention.

More information

The U.S. National Institute of Arthritis and Musculoskeletal and Skin Diseases has more about arthritis.