Osteoarthritis Epidemiology
Abstract 929 Mortality And Complication Rates Following Primary And Revision Total Hip Replacement Are Inversely Related To Hospital And Surgeon Procedure Volume
JN Katz, J Barrett, N Mahomed, CB Phillips, W Harris, JA Baron Boston, MA, Hanover, NH, Toronto, ON
The quantity of total hip replacement (THR) operations performed annually in the United States has risen markedly over the last two decades. The leading indication for these operations is osteoarthritis. These investigators sought to determine whether morbidity and mortality following such surgery is related to the hospitals and surgeons procedure volume. These questions were addressed using the Medicare claims database. 58,521 elective primary and 12,956 revision THRs were performed in Medicare beneficiaries from July 1995 - June 1996. These analyses revealed that higher volume hospitals and surgeons experienced lower complication and mortality rates.
Editorial Comments: These findings are intriguing, in that the smaller volume hospitals that experience the higher complication rates also perform the majority of the THR procedures. This data set, however, is limited by the lack of clinical records that might indicate whether comorbidity or more severe preoperative arthritis status might explain some of these disparate results between the low and high volume hospitals.
Abstract 564 The Relationship Of Bone Density To The Subsequent Incidence And Progression Of Radiographic Osteoarthritis Of The Knee: The Chingford Study
DJ Hart, DV Doyle, TD Spector London, United Kingdom
Osteoarthritis and osteoporosis are often considered to be inversely related; the presence of one precludes the coexistence of the other. These investigators examined 830 women in The Chingford Study to determine the relation of bone mineral density at cohort entry to the development and progression of knee OA. The women had serial weight-bearing knee X-rays performed 4 years apart. BMD at baseline was assessed in the lumbar spine and hip. Higher spine and hip BMD were in fact related to incident knee osteophytes. In contrast, progression of hip osteophytes was not associated with spine BMD, yet hip BMD was modestly reduced in those women with progressive knee OA.
Editorial Comments: The relationship of osteoarthritis to osteoporosis remains an active area of inquiry, as investigators at many centers further study these two highly prevalent disorders associated with aging.
Abstract 568 The Association Of Nitrate Use And Incident Radiographic Hip Osteoarthritis In Older White Women
NE Lane, MC Nevitt, E Williams, SR Cummings, MC Hochberg SF, CA, Baltimore, MD
Nitric oxide has been implicated as a possible mediator of osteoarthritis development. Given this finding from the laboratory, the investigators sought to determine, using a cohort of elderly white women, if use of nitrates was related to incidence of hip osteoarthritis. Nitrate use was determined based on interview and review of prescription labels. Daily and any, but not intermittent, nitrate use was associated with a twofold increased risk of new hip osteoarthritis.
Editorial Comments: These results are of interest, and seem to link a laboratory-based finding to epidemiologic evidence. Nevertheless, it is not known whether nitrates, taken in pharmacologic doses to treat heart disease, are active at the level of the joint. Alternately, nitrates may be a marker for a cardiovascular disease profile that in itself may be related to osteoarthritis. It thus still appears premature to advocate use of inhibitors of nitric oxide as a preventive measure for osteoarthritis.
Abstract 1359 Association Of Oral Estrogen Use With Incident Radiographic Hip OA In Older White Women
For the Study of Osteoporosis Fractures (SQF) Research Group, MC Nevitt, NE Lane, MC Hochberg
Baseline data from the Study of Osteoporotic Fractures have previously demonstrated that prevalent hip OA in older white women is related to use of estrogen replacement therapy (ERT), with long term users of ERT exhibiting a lower prevalence of OA. In this data set, the investigators now examined the relation of estrogen use to incident hip OA. Two pelvic X-rays, a mean of 8 years apart, were use to determine incident cases of hip OA. Users of estrogen replacement experienced a 50% increased risk of incident joint space narrowing. However, estrogen use was not related to incident joint osteophytes.
Editorial Comment: Thus, in this cohort of elderly white women (in which use of estrogen replacement appears is associated with lower prevalence of hip OA), the relation of estrogen use to incident OA is equivocal. There appears to be a modest increased risk of joint space narrowing, but perhaps also a borderline protective effect against joint osteophytes associated with ERT use.
Abstract 1358 High Serum Alpha-Tocopherol In Relation To Gamma Tocopherol May Protect Against Knee OA
JM Jordan, AJ De Roos, L Kohlmeier, JB Renner, N Craft, MC Hochberg, CG Helmick Chapel Hill, NC, Wilson, NC, Baltimore, MD, Atlanta, GA
There has been much interest, particularly among the public, about the relation of diet and vitamin intake to osteoarthritis. The investigators examined data from the Johnston County Osteoarthritis Project to determine the relation of serum levels of (a) alpha-tocopherol, (b) gamma-tocopherol, and (c) the ration of alpha to gamma tocopherol to prevalent knee OA. These serum levels were compared among 200 cases with radiographic knee OA and 200 age, gender, and race-matched controls. The highest tertile of the alpha-to-gamma tocopherol ratio displayed half the risk of knee OA, compared to those in the lowest tertile (odds ratio [OR] 0.51). Similarly, the highest compared to the lowest tertile of serum gamma tocopherol was associated with almost twice the prevalence of knee OA (OR of 1.98). In contrast, serum alpha tocopherol level was not related to knee OA.
Editorial Comment: It will be of interest to know, in anticipated future analyses from this cohort, whether alpha and gamma tocopherol levels and their ratio will be related to incident and progressive knee OA.