European guidelines on diagnosing hand osteoarthritis aim to be more clinically useful in the practice setting than the 1990 classification criteria from the American College of Rheumatology, according to their authors.
“Until now, the main reference cited for the diagnosis [of hand osteoarthritis] has been the [American College of Rheumatology] criteria,” noted the authors of the guidelines issued by the European League Against Rheumatism (EULAR). The ACR criteria focus more on classifying disease rather than diagnosing it, they stated, adding that the updated guidelines provide evidence-based guidance from a multidisciplinary team of physicians representing 15 countries.
The strength of EULAR's recommendations is ranked 1–100 based on the quality of the supportive evidence. A strength of 100 is fully recommended and 0 is not at all recommended.
The first recommendation (strength: 69) spells out risk factors for hand OA, which include female sex, age over 40 years, family history of the disease, obesity, joint injury, and certain occupations. Although a reduction in estrogen at menopause may also be a risk factor for hand OA, this evidence is not supported by findings from hormone therapy (HT) studies. However, “as these studies were observational studies, they may be confounded by the increased bone density [a potential risk factor for hand OA] due to HT,” which would necessitate further studies on the link between estrogen and hand OA (Ann. Rheum. Dis. 2008 Feb. 4 [doi 10.1136/ard.2007.084772]).
“Pain on usage has limited value for the diagnosis of hand OA,” due to its extremely low sensitivity (strength: 85), wrote the investigators. “Limited duration of localized morning or inactivity stiffness is more specific to hand OA than inflammatory arthritis (stiffness persists 22 minutes on average for hand OA versus 58 minutes for rheumatoid arthritis affecting the hand).” Pain that is specific to the distal interphalangeal, proximal interphalangeal, and thumb base joints is also a hallmark of the disease.
Heberden's and Bouchard's nodes, which “have limited value as a single diagnostic marker” are nevertheless important, “especially when used in combination with other features of hand OA” (strength: 80).
The investigators also state that functional impairment resulting from hand OA may be as severe as is seen with rheumatoid arthritis (strength: 57).
As to associations between hand OA and other diseases, the authors wrote that “patients with hand OA have increased risk of both knee OA ([odds ratio] = 3.0, 95% [confidence interval] 1.2, 7.5) and hip OA (OR = 3.25, 95% CI 2.19, 4.84)” (strength: 77). However, “there is no clear justification to include assessment of other target joints for OA for the purpose of diagnosis and treatment planning of hand OA.”
The recommendations acknowledge that there may be specific subsets of hand OA, including interphalangeal joint (IPJ) OA (which can occur with or without nodes), thumb-base OA, and erosive OA, all of which carry unique risk factors, associations, and outcomes. “For example, hypermobility has been reported as a risk factor for thumb-base OA but a negative risk ('protective') factor for IPJ OA,” the researchers wrote (strength: 68). Furthermore, “erosive hand OA targets IPJs and shows radiographic subchondreal erosion, which may progress to marked bone and cartilage attrition.” In general, this type of OA has worse outcomes than nonerosive IPJ OA, they point out (strength: 87).
However, Dr. Altman expressed skepticism of this conclusion. “The question as to whether the erosive form of hand OA is indeed a separate subset or whether it is part of the spectrum of disease has been addressed but may not have been answered in this report,” said Dr. Altman, who is also professor of medicine of the University of California, Los Angeles.
A final recommendation states that since inflammatory markers like erythrocyte sedimentation rate, rheumatoid factor, and C-reactive protein are not typically elevated in patients with hand OA, blood tests are not required for a diagnosis. However, blood tests “may be required to exclude coexistent disease” (strength: 78).