Background Hand involvement is one of the major determinants of disease outcome affecting the ability to perform activities of daily living and other functional activities in rheumatoid arthritis (RA). Handgrip strength (HS) provides a clinically validated marker of functional disability.

Objectives The aim of this study was to assess discriminant validity of HS and to compare it with the Quick Disabilities of Arm Shoulder and Hand (Quick-DASH) (1), Arthritis Impact Measurement Scales 2 (AIMS-2), Hand Health Assessment Questionnaire (Hand HAQ) and Recent-Onset Arthritis Disability (ROAD) upper extremity index (2).

Methods In this transversal study, a total of 291 patients with RA responding to the ACR 2010 criteria were evaluated. HS was measured twice for both hands by the use of an electronic grip device. The instrument consists of a cylindrical-shape grip device made of 5 force sensors connected to a microcontroller. The correlations between indices were studied through the Pearson’s correlation coefficient (r). The discriminatory ability of HS [cut-off values, male ≤ 27Kg, female ≤16Kg], QuickDASH [range 0-100], AIMS-2 hand/finger function [range 0-10], Hand HAQ [range 0-21], and ROAD upper extremity function [range 0-10] were assessed using receiver operating characteristic (ROC) curves analysis. The external anchor was the general question on Patient Acceptable Symptom State (PASS) (3).

Results The 239 female and 52 male patients (sex ratio: 4.5F/1M) were of a mean age of 56.5 ±12.3 years (20–81) and a disease duration of 8.5±3.3 years (2 months–22 years). The HS mean (Kg) was 20.9±7.1 [95%CI 20.07-21.7]. The Quick-DASH mean was 28.08±11.90 [95%CI 26.7–29.45]. The AIMS-2 hand and finger mean score was 4.5±2.21 [95%CI 4.24–4.75]. The Hand HAQ mean score was 9.8±4.3 [95%CI 9.3-10.31] and the ROAD-upper extremity mean score was 4.75±2.11 [95%CI 4.5–5]. A positive statistically significant correlation was noted between the five indices (p<0.0001). The area under the ROC (AUC-ROC) were similar in all the measures although the HS showed the greatest discriminative ability (Table I and Figure 1).

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Figure 1

ROC of measures of upper extremity disease activity measures used in rheumatoid arthritis. ROC illustrating the relationship between sensitivity and complement of specificity (100-specificity) in RA for functional measures using PASS as an external indicator.

Conclusion HS is a good alternative to the self-assessment functional indices for the evaluation of functional disability in RA. The use of an electronic grip device for HS measurement makes it easier to collect data and should be applied in both clinical trials and routine clinical care settings.

References [1] Salaffi F, Di Carlo M, Carotti M, Farah S. “Validity and interpretability of the QuickDASH in the assessment of hand disability in rheumatoid arthritis”. Rheumatol Int. 2018Dec3.

[2] Salaffi F, Carotti M, Gutierrez M, Di Carlo M, De Angelis R. “Patient Acceptable Symptom State in Self-Report Questionnaires and Composite Clinical Disease Index for Assessing Rheumatoid Arthritis Activity: Identification of Cut-Off Points for Routine Care”. Biomed Res Int. 2015

[3] Salaffi F, Stancati A, Neri R, Grassi W, Bombardieri S. “Measuring functional disability in early rheumatoid arthritis: the validity, reliability and responsiveness of the Recent-Onset Arthritis Disability (ROAD) index”. Clin Exp Rheumatol. 2005 Sep-Oct;23(5 Suppl 39):S31-42.

Disclosure of Interests Fausto Salaffi Grant/research support from: Abbvie, Roche, Novartis, BMS, Pfizer, Sanofi, Speakers bureau: Abbvie, Roche, Novartis, Pfizer, Sanofi, BMS, sonia farah: None declared, Marco Di Carlo: None declared, giacomo beci: None declared, marina carotti Speakers bureau: abbvie pfizer novartis roche bms sanofi