RESEARCH - Reproductive history, hormonal factors and the incidence of hip and knee replacement for OA in middle-aged women

[Guest guest]

Ann Rheum Dis. Published Online First: 28 October 2008.

doi:10.1136/ard.2008.095653

--------------------------------------------------------------------------------

Extended Report

Reproductive history, hormonal factors and the incidence of hip and

knee replacement for osteoarthritis in middle-aged women

Bette Liu 1*, Balkwill 1, Cyrus 2, Roddam 1,

Brown 1 and Beral 1

1 Cancer Epidemiology Unit, University of Oxford, United Kingdom

2 MRC Epidemiology Resource Centre/Botnar Research Centre, United Kingdom

Abstract

Objectives: To examine the effect of reproductive history and use of

hormonal therapies on the risk of hip and knee joint replacement for

osteoarthritis.

Methods: Prospective study of 1.3 million women aged on average 56

years at recruitment and followed-up through linkage to routinely

collected hospital admission records. The adjusted relative risk of

hip and knee replacement for osteoarthritis was examined in relation

to parity, age at menarche, menopausal status, age at menopause, and

use of hormonal therapies.

Results: Over a mean of 6.1 person-years of follow-up 12,124 women had

a hip replacement and 9,977 a knee replacement. The risk of joint

replacement increased with increasing parity and the effect was

greater for the knee than the hip: increase in relative risk of 2%

(95%CI 1-4%) per birth for hip replacement and 8% (95%CI 6-10%) for

knee replacement. An early age at menarche slightly increased the risk

of both hip and knee replacement (relative risk for menarche ¡Ü11yrs

versus 12yrs 1.09(95%CI 1.03-1.16) and 1.15(95%CI 1.08-1.22)

respectively). Menopausal status and age at menopause were not clearly

associated with risk. Current use of post-menopausal hormone therapy

was associated with a significant increase in the incidence of both

hip and knee replacement (RR=1.38(95%CI 1.30-1.46) and RR=1.58(95%CI

1.48-1.69) respectively) while previous use of oral contraceptives was

not (RR=1.02(95%CI 0.98-1.06) and RR=1.00(95%CI 0.96-1.04) for hip and

knee respectively).

Conclusions: Hormonal and reproductive factors affect the risk of hip

and knee replacement, more so for the knee than the hip. The reasons

for this are unclear.

http://ard.bmj.com/cgi/content/abstract/ard.2008.095653v1?papetoc

Not an MD