The decrease in grip strength in aromatase inhibitor-induced arthralgia is associated with extremes in body mass index and increased tenosynovial abnormalities.
Authors: Morales L , Pans S , Van Hoydonck M , Verschueren K , Van Calster B , Paridaens R , Westhovens R , Timmerman D , De Smet L , Vergote I , Christiaens M , Neven P 
Published: December 2010

Abstract
Abstract #1141
Background: We previously demonstrated in 17 patients that aromatase inhibitor (AI)-induced arthralgia is associated with a decrease in grip strength corresponding to an increase in tenosynovial abnormalities on magnetic resonance imaging (MRI). It is important to identify patients at risk of developing arthralgia and its associated functional and tenosynovial changes. Reports on the effect of weight on AI-induced arthralgia are conflicting. Our purpose was to investigate the effect of body mass index (BMI) and tenosynovial abnormalities on grip strength.&#x2028; Patients and Methods: This is a prospective single-centre study including consecutive postmenopausal patients with early breast cancer receiving either tamoxifen or an AI. At baseline and after 6 months, patients filled in a rheumatologic history questionnaire and a rheumatologic examination including a grip strength test was done. At the same time points, MRI of both hands and wrists was performed. The primary endpoint was tenosynovial abnormalities from baseline on MRI. Secondary endpoints were changes from baseline for morning stiffness, grip strength and intra-articular fluid on MRI. Wilcoxon signed ranks was used to test changes from baseline and the Spearman correlation coefficient to assess the association between rheumatologic and MRI changes from baseline. Regular and robust regression analysis was employed to investigate the influence of BMI on grip strength.&#x2028; Results: Thirty three patients completed all the planned investigations and are included in this report (27 patients on AI and 6 on tamoxifen). Median age was 64 years (range 51-74) and median BMI was 24 kg/m2 (range18-45). At 6 months, patients on AI experienced increased morning stiffness (p&lt;0.05), decrease in grip strength (p&gt;0.005), increase in tenosynovial abnormalities (p&lt;0.001) and increase in intra-articular fluid (p&lt;0.001). Only minor changes were seen in patients on tamoxifen. The decrease in grip strength correlated with the tenosynovial changes on MRI (p=0.05) but was not significantly correlated with intra-articular fluid (p=0.3). The regression analysis suggests that grip strength is predicted to decrease more strongly for extremes in BMI (very high and very low BMI) and least strongly for a BMI around 25. Furthermore, the effect of tenosynovial abnormalities on decrease in grip strength does not diminish when the effect of BMI is accounted for.&#x2028; Conclusion: The functional impairment of hands in the AI-induced arthralgia is characterized by tenosynovial changes on MRI correlating with a significant decrease in hand grip strength. Grip strength is predicted to decrease more strongly for extremes in BMI and higher levels of tenosynovial abnormalities.
Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1141.