FRI0647 Estimation of minimum clinically important difference in fibromyalgia for fiqr using bpi as the anchor measure
Authors: S. Surendran, C. B. Mithun
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background:</h3> The FIQ (Fibromyalgia Impact Questionnaire) was first published in 1991 and had 19 items which were recalled over a week. The scoring system is highly reliable and is recognised as an outcome measure that covers the multiple domains of Fibromyalgia<sup>1</sup>. A prior study by Benett et al<sup>2</sup> have shown that 14% change in the FIQ total score represents the Minimum Clinically Important Difference(MCID) in the Fibromyalgia. The FIQ was revised in 2009 to the 20 item Fibromyalgia Impact Questionnaire Revised or FIQR. However, there has been no study done for assessing the MCID of the FIQR in Fibromyalgia. <h3>Objectives:</h3> The aim of our study is to estimate the MCID for Fibromyalgia Impact Questionnaire Revised using anchor-based methodology with average pain score on Brief Pain Inventory as the anchor. <h3>Methods:</h3> We have used data from our prospectively followed cohort of fibromyalgia patients. They were treated as per protocol with duloxetine in escalating doses. Data from this cohort was used to estimate the MCID for the FIQR using anchor-based methodology The anchor used was the average pain score on Brief Pain Inventory(BPI). The MCID for BPI average pain score was calculated by Mease et al to be 30%<sup>3</sup>. Thus, all patients in our cohort having an improvement of greater than 30 % were classified as responders. All other patients were non-responders. Within these two groups, the means and standard deviations of the FIQR scores at baseline and at the end of treatment were obtained. The MCID was calculated as the difference in the unadjusted mean change in the FIQR scores between the "non-responder" group and the group with "responder group". It was also expressed as a percentage reduction from the mean baseline FIQR. <h3>Results:</h3> <h3>Conclusions:</h3> Based on our data, we suggest that a "27.04 point" or "45.5 %" improvement on the FIQR score represents the minimum clinically important difference for FIQR in fibromyalgia patients presenting with moderate to severe pain. Strengths of this work include the usage of prospectively followed patient population for analysis, protocol-based treatment with duloxetine and representation of a local population which more is applicable to our clinical practice. That MCID obtained for the FIQR score is much higher than the 14 % which was the MCID obtained for the older FIQ score may suggest a population-based variation in improvement of outcome measures. <h3>References</h3> 1. Williams DA, Arnold LM. Measures Applied to the Assessment of Fibromyalgia. Arthritis Care Res. 2011;63(2):1487–1495. doi:10.1002/acr.20531. Measures 2. Bennett RM, Bushmakin AG, Cappelleri JC, Zlateva G, Sadosky AB. Minimal clinically important difference in the fibromyalgia impact questionnaire. J Rheumatol. 2009;36(6):1304–1311. doi:10.3899/jrheum.081090 3. Mease PJ, Spaeth M, Clauw DJ, et al. Estimation of minimum clinically important difference for pain in fibromyalgia. Arthritis Care Res. 2011;63(6):821–826. doi:10.1002/acr.20449 <h3>Acknowledgements:</h3> We would like to acknowledge and thank the statistical assistance provided by Mrs Renjitha Bhaskaran from the Department of Biostatistics at Amrita Vishwavidyapeetham University. <h3>Disclosure of Interest:</h3> None declared