Objective. The objective of this study was to compare the impact of psoriatic disease (psoriatic arthritis [PsA] and psoriasis) and rheumatoid arthritis (RA) on objective and subjective parameters of hand function. Methods. Hand function was determined in this cross-sectional study by 1) vigorimetric grip strength, 2) the Moberg Picking-Up Test used for assessing fine-motor skills, and 3) self-reported hand function (Michigan Hand Questionnaire). Mixed-effects linear regression models were used to test the relation of hand function with disease group, age, and sex. Results. Two hundred ninety-nine subjects were tested, 101 with RA, 92 with PsA, and 106 nonarthritic controls (51 with psoriasis and 55 healthy controls [HCs]). Regression analysis showed that hand function was influenced by age, sex, disease group, and hand dominance (P < 0.001 for all). The impact of PsA and RA on hand function was comparable and generally more pronounced in women. Both PsA and RA led to significantly enhanced age-related loss of grip strength, fine-motor skills, and self-reported hand function in patients with PsA and RA compared with HCs. In addition, patients with psoriasis showed significant impairment of hand function compared with HCs. Conclusion. RA and PsA have a comparable impact on the decline of strength, fine-motor skills, and self-reported function of the hand. Unexpectedly, patients with psoriasis also show impaired hand function that follows a similar pattern as observed in patients with PsA.

Background:Inflammatory-rheumatic diseases affect hand joints with swelling and pain, leading to joint destruction. Even patients with psoriasis only may suffer subclinical inflammation in the hand joints, leading to changes of bone [1]. Finger joint involvement is different for rheumatoid arthritis (RA), psoriatic arthritis (PsA) and psoriasis (Pso) but hand function in these patients is not well characterized.Objectives:To quantify and compare grip strength and hand function in patients with RA, PsA and Pso and to relate these outcomes to disease activity.Figure 1Methods:Patient diagnosed with RA (ACR/EULAR 2010), PsA (Caspar) and Pso and 54 healthy individuals were included in the study after written informed consent. Maximal isometric grip strength (kPA) was measured with a hand dynamometer (Lafayette Instrument, Lafayette, IN, USA) as the highest value out of three measurements. Hand function was determined by way of the Moberg Picking-Up Test (MPUT) and the fastest (s) of two measurements was used. Disease activity was calculated as DAS28_ESR and TJC/SJC 78/76 was recorded. One-way Analysis of Variance (ANOVA), factorial ANOVA and Games-Howell post-hoc testing was performed (p<0.05).Results:101 RA (63 f; 38 m; age: 59.1±13.2 yrs), 92 PsA (48 f, 44 m; age 54.8±11.6 yrs) and 51 Pso patients (19 f, 32 m; age 47.3±14.1 yrs), as well as 54 healthy control subjects (30 f, 24 m; age 54.6± 16.5 yrs) participated in the study. Disease duration (yrs) was not different between groups (RA: 11.03±10.1, PsA: 9.1±9.75, Pso: 12.5±11.7; p=0.156) but Pso patients in our cohort were younger compared to RA and PsA patients. Mean DAS28_ESR was < 3.2 for all patient groups with control subjects (DAS28 1.6 ± 0.7) having lower scores compared to all patient groups and Pso patients presenting with lower DAS28 (2.3±1.3) compared to RA (3.0±1.3) and PsA (2.9±1.3). While TJC was higher for all patients compared to controls (RA: 5.2±6.8, PsA: 5.9±8.1 Pso: 3.2±6.4; CON: 0.5±1.4; p=0.00), SJC was higher for RA and PsA compared to Pso and CON (RA: 0.7±1.0, PsA: 0.9±2.2 Pso: 0.1±0.3; CON: 0.5±1.4; p=0.000). Grip strength of the dominant and/or affected hand of RA patients was lower compared to PsA, Pso and CON (Figure 1A). In contrast to this, hand function of the same hand in all tested patient groups was reduced compared to CON (Figure 1B). The results for grip strength and hand function were not different for the dominant and the affected hand and are independent of age differences between groups.Conclusion:Overall, RA patients showed significantly lower grip strength compared to PsA and Pso patients as well as to the control group, whereas all three patient groups performed worse in the MPUT compared to the control cohort. This suggests that grip strength may be preserved longer than hand function in patients with inflammatory rheumatic disease. Further, it was surprizing that hand function was reduced in Pso patients without arthritic correlate compared to healthy subjects. This suggests that hand function may provide a potential param...

BackgroundMonitoring disease activity in patients with inflammatory arthritis is essential for effective treatment. While the health assessment questionnaire (HAQ) is commonly used to assess physical function, additional functional tests, such as isometric grip strength and the Moberg Pick-Up-Test (MPUT), provide objective measures for hand function and allow assessing hand function across different diseases (1). It remains unclear to date, if measured hand function is already reflected by the HAQ, as the most widely used patient reported outcome measure of physical function in arthritis.ObjectivesTo estimate the proportion of hand function and grip strength variability explained by HAQ, patient-reported hand function, and between-person variation in patients with inflammatory arthritis and non-arthritic controls.MethodsPatients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), psoriasis without PsA (PsO) and healthy controls (HC) were investigated. Subject characteristics (age, sex, disease) and HAQ were recorded. Hand function was assessed by vigorimetric grip strength, MPUT, and a patient-reported tool (Michigan Hand Questionnaire, MHQ). Mixed pure-random-effect linear regression models were used to estimate the proportion of variance in measured hand function or grip strength explained by subject characteristics (age, hand dominance, sex, reported hand function, disease group).Results299 subjects were tested, 101 with RA (Age: 59.1±13.3 years, BMI: 27.2±5 kg/m2, HAQ-DI score: 0.9±06), 92 with PsA (Age: 58.8±11.6 years, BMI: 29±6.1kg/m2, HAQ-DI score: 0.6±0.7) and 106 non-arthritic controls (51 with Pso (Age: 47.3±14.1 years, BMI: 29.8±7.3 kg/m2, HAQ-DI score: 0.4±06) and 55 HC (Age: 54.6±16.5 years, BMI: 25.2±3.3 kg/m2, HAQ-DI score: 0.1±0.2). Overall variation of MPUT is mostly accounted for by between-person variation (43.1%), followed by HAQ (20.3%) and MHQ (20.2%) (Figure 1A). Overall variation in grip strength is mostly accounted for by sex (59.8%), between-person variation (21.1%) and HAQ (11.3%) (Figure 1B). Overall variation in MHQ is mostly accounted for by HAQ (59.2%) and residual variation (28.3%). Study group specific result are summarized in Table 1.Table 1.Variance proportions for each of the four study groups.Variance proportions (%)Hand function (MPUT)Grip strengthGroupControlPsAPsORAControlPsAPsORAMHQ3.439.00.00.00.02.10.00.0ID34.836.251.652.816.112.921.327.9Age0.013.80.00.78.48.40.00.0HAQ35.810.834.316.43.83.110.312.0Dominant hand0.60.20.00.03.50.61.30.2Sex12.10.00.04.364.268.963.755.0Residual13.30.014.125.83.94.03.45.0ConclusionWhile the variance variation in grip strength is mainly explained by sex and between-person variation for all subject groups, the proportions of explained variance for measured hand function is not similar between diseases. In all groups > 50% of the variation in measured hand function remains unexplained by the variables used. Especially in arthritis patients, HAQ explained less than 25% of the variance in measured hand function. Grip-strength can be considered a poor surrogate for hand function in this context due to its large gender dependence. The explainability of MHQ variation largely by HAQ indicates that it has limited potential to provide further information beyond overall functional impairment. In contrast, the large between-person variation in MPUT likely indicates unexplored movement patterns of hand motion that may be further dissected using sensor-based analyses (2) and can help identify movement components a potential for an in-depth assessment of subtle hand-function alterations in inflammatory arthritis.References[1]Liphardt AM et al. ACR Open Rheumatol 2020, 2, 734-740. 2. Phutane U et al. Sensors (Basel) 2021, 21.AcknowledgementsThis study was supported by the German Research Council (SFB 1483 – Project-ID 442419336, INST 90 / 985-1 FUGG, FOR2438/2886; SFB1181), the German Ministry of Science and Education (project MASCARA), the European Union (H2020 GA 810316 - 4D-Nanoscope European Research Council Synergy Project) and Novartis Germany GmbH.Disclosure of InterestsNone declared