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Increasing Prevalence of Knee Pain and Symptomatic Knee Osteoarthritis: Survey and Cohort Data

Uyen-Sa D.T. Nguyen, DSc; Yuqing Zhang, DSc; Yanyan Zhu, PhD; Jingbo Niu, MD, DSc; Bin Zhang, ScD; and David T. Felson, MD, MPH
[+] Article and Author Information

From Clinical Epidemiology Research & Training Unit, Boston University School of Medicine, and Brigham and Women's Hospital, Boston, Massachusetts.


Acknowledgment: The authors thank the FOA Study research team and study participants for the contribution of their time, effort, and dedication. They also thank the National Center for Health Statistics for access to NHANES data. Finally, they thank Piran Aliabadi, MD, for expertise and assistance in reading Framingham Study radiographs.

Grant Support: By the National Institutes of Health (NIH AR47785 and AG18393) and an American College of Rheumatology Research and Education Foundation Rheumatology Scientist Development Award (Dr. Nguyen). The Framingham Heart Study was funded by the National Heart, Lung, and Blood Institute, National Institutes of Health (NHLBI/NIH contract N01-HC-25195), and the FOA Study was funded by the National Institute on Aging and National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health.

Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M11-1776.

Reproducible Research Statement:Study protocol and statistical code: Not available. Data set: NHANES data are available at www.cdc.gov/nchs/nhanes.htm; data from the Framingham Heart Study and the FOA Study are available after approval from Boston University (see www.framinghamheartstudy.org).

Requests for Single Reprints: David T. Felson, MD, MPH, Boston University School of Medicine, Clinical Epidemiology Research and Training Unit, 650 Albany Street, Suite X200, Boston, MA 02118.

Current Author Addresses: Drs. Nguyen, Y. Zhang, Zhu, Niu, B. Zhang, and Felson: Boston University School of Medicine, Clinical Epidemiology Research and Training Unit, 650 Albany Street, Suite X200, Boston, MA 02118.

Author Contributions: Conception and design: U.S.D.T. Nguyen, D.T. Felson.

Analysis and interpretation of the data: U.S.D.T. Nguyen, Y. Zhu, J. Niu, B. Zhang, D.T. Felson.

Drafting of the article: U.S.D.T. Nguyen, J. Niu, B. Zhang, D.T. Felson.

Critical revision of the article for important intellectual content: U.S.D.T. Nguyen, Y. Zhu, B. Zhang.

Final approval of the article: U.S.D.T. Nguyen, Y. Zhu, J. Niu, B. Zhang, D.T. Felson.

Provision of study materials or patients: D.T. Felson.

Statistical expertise: U.S.D.T. Nguyen, Y. Zhu, B. Zhang.

Obtaining of funding: D.T. Felson.

Administrative, technical, or logistic support: D.T. Felson.

Collection and assembly of data: J. Niu, D.T. Felson.


Ann Intern Med. 2011;155(11):725-732. doi:10.7326/0003-4819-155-11-201112060-00004
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Background: A recent surge in knee replacements is assumed to be due to aging and increased obesity of the U.S. population.

Objective: To assess whether age, obesity, and change in radiographic knee osteoarthritis explain the trend in knee pain and osteoarthritis.

Design: Cross-sectional, using data from 6 NHANES (National Health and Nutrition Examination Survey) surveys between 1971 and 2004 and from 3 examination periods in the FOA (Framingham Osteoarthritis) Study between 1983 through 2005.

Setting: U.S. population.

Participants: NHANES participants (white or African American; aged 60 to 74 years) and FOA Study participants (mostly white; aged ≥70 years) were included.

Measurements: NHANES participants were asked about pain in or around the knee on most days. In the FOA Study, participants were asked about knee pain and had bilateral weight-bearing anteroposterior knee radiography to define radiographic knee osteoarthritis. Radiographic evidence and self-reported pain were used to define symptomatic knee osteoarthritis. The age- and age- and body mass index (BMI)–adjusted prevalences of knee pain and osteoarthritis at later examinations were compared with that of earlier examinations by using the ratio of the prevalence estimates.

Results: Age- and BMI-adjusted prevalence of knee pain increased by about 65% in NHANES from 1974 to 1994 among non-Hispanic white and Mexican American men and women and among African American women. In the FOA Study, the age- and BMI-adjusted prevalence of knee pain and symptomatic knee osteoarthritis approximately doubled in women and tripled in men over 20 years. No such trend was observed in the prevalence of radiographic knee osteoarthritis in FOA Study participants. After age adjustment, additional adjustment for BMI resulted in a 10% to 25% decrease in the prevalence ratios for knee pain and symptomatic knee osteoarthritis.

Limitations: Differences in sampling of FOA Study participants over time or birth cohort effects cannot be ruled out as possible explanations of the increased reporting of knee pain. Increases in prevalence at the last interval in the FOA Study might be due to differences in cohort membership by interval.

Conclusion: Results suggest that the prevalence of knee pain has increased substantially over 20 years, independent of age and BMI. Obesity accounted for only part of this increase. Symptomatic knee osteoarthritis increased but radiographic knee osteoarthritis did not.

Primary Funding Source: American College of Rheumatology Research and Education Foundation and National Institutes of Health. The FOA Study was funded by the National Heart, Lung, and Blood Institute (for the parent Framingham Heart Study), National Institute on Aging, and National Institute of Arthritis and Musculoskeletal and Skin Diseases (FOA Study), National Institutes of Health.

Figures

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Figure 1.
Sampling weighted and age- and BMI-adjusted prevalence (95% CI) of knee pain for non-Hispanic white and Mexican American participants across 6 NHANES surveys.

Test for trend from 1974 to 1994: P = 0.003 (men) and P = 0.002 (women). Test for trend from 1999 to 2004: P = 0.090 (men) and P = 0.012 (women). The prevalences in African American participants over the first 3 NHANES were 12.6%, 10.7%, and 15.6% (P = 0.35), respectively, for men and 16.7%, 22.0%, and 28.7% (P = 0.037), respectively, for women. For the subsequent 3 continuous NHANES, the corresponding prevalences were 7.9%, 16.6%, and 18.6% (P = 0.22) for men and 13.8%, 22.2%, and 29.9% (P = 0.003) for women. BMI = body mass index; NHANES = National Health and Nutrition Examination Survey.

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Figure 2.
Age- and BMI-adjusted prevalence (95% CI) of knee pain for participants in the Framingham Osteoarthritis Study across 3 examination periods.

Test for trend: P < 0.001 (men and women). BMI = body mass index.

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Grahic Jump Location
Figure 3.
Age- and BMI-adjusted prevalence (95% CI) of radiographic and symptomatic knee OA for participants in the Framingham Osteoarthritis Study across 3 examination periods.

For radiographic knee OA (Kellgren–Lawrence score ≥2), test for trend from 1983 to 2005: P = 0.82 (men) and P = 0.036 (women). For symptomatic knee OA (knee pain in the knee with radiographic OA), test for trend from 1983 to 2005: P < 0.001 (men) and P = 0.006 (women). BMI = body mass index; OA = osteoarthritis.

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Summary for Patients

Trends in Knee Pain and Knee Osteoarthritis

The full report is titled “Increasing Prevalence of Knee Pain and Symptomatic Knee Osteoarthritis: Survey and Cohort Data.” It is in the 6 December 2011 issue of Annals of Internal Medicine (volume 155, pages 725-732). The authors are U.S.D.T. Nguyen, Y. Zhang, Y. Zhu, J. Niu, B. Zhang, and D.T. Felson.

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