A comparison of the indicators of hand function in early RA populations from the UK and China

Abstract

Background:
Rheumatoid arthritis (RA) is a universal disease with clinical presentations and impacts varying in different ethnic groups. The process of inflammatory joint damage quantified by ESR, CRP, number of tender and swollen joints can lead to structural impairment and deformity of wrists and hands. However, the relationship between hand impairment and disability in early RA is controversial. A comparison of this relationship in different population groups would add to the understanding of country-specific impacts of RA. This study compared the correlations of disease activity and hand impairment with self-report hand function between two early RA populations from the UK and China.

Methods: A cohort comparison study was conducted. 60 Chinese patients recruited from Shanghai, China were matched on gender and age with 60 patients from a prospective early RA cohort from the UK (SARAH trial). The procedures of data collection in China followed the standard operating procedures employed in the SARAH trial. Outcome measures including MHQ, medical history and physical assessments were used to assess disease activity, hand impairment and function.

Results:
There was no significant association (P?0.05) between hand function with MCP joint deformity in either population group. Correlations between hand function with range of movement measured by active wrist flexion, combined finger flexion and composite finger extension were weak in both the UK and Chinese population (r?0.04, p?0.05). The associations between self-report overall hand function and full grip strength were moderate to weak in Chinese patients (dominant r=0.473 and non-dominant r=0.347, p?0.05). The correlations were weak between overall hand function and pinch grip among Chinese patients (p?0.05). However, correlations between hand function and full grip strength were moderate in UK patients (dominant r=0.582 and non-dominant r=0.555, p?0.05). Moderate relationships were found between hand function and pinch strength in the UK patients (dominant r=0.647 and non-dominant r=0.624, p?0.05). There were strong to moderate negative correlations between hand function and pain in both population groups (UK r=-0.690 and China r=-0.458, p?0.05). A moderate negative correlation was found between hand function and swelling (r=-0.45, p?0.001) and a moderate correlation between dexterity and hand function (dominant r=0.441, non-dominant r=0.440, p?0.05) in Chinese patients. However, no significant association (P?0.05) was found between hand function and swelling or hand function and dexterity among UK patients.

Conclusion: In early RA populations in both the UK and China, hand strength, range of movement and pain are indicators of hand function. There is a weaker correlation between hand strength with self-reported hand function in the Chinese population compared with the UK RA patients. Swelling is not an indicator of hand function in the UK population.
Test
Overall hand function (dominant hand)
China (dominant hand) UK (dominant hand) China (non-dominant hand) UK (non-dominant hand)
Correlation P-value Correlation P-value Correlation P-value Correlation P-value
Spearman’s rho MCP joint Deformity -0.321 0.221 0.121 0.359 -0.210 0.107 0.055 0.067
Pearson r Active wrist extension 0.025 0.850 0.023 0.864 -0.025 0.850 0.864 0.023
Pearson r Active wrist flexion 0.290 0.025 0.276 0.033 0.328 0.010 0.338 0.008
Spearman’s rho Combined finger flexion -0.381 0.003 -0.350 0.007 -0.357 0.005 -0.361 0.005
Pearson r Composite finger extension 0.379 0.003 0.394 0.002 0.405 0.001 0.189 0.152
Spearman’s rho Dexterity 0.441 0.000 -0.123 0.354 0.440 0.000 0.086 0.515
Spearman’s rho Full grip strength 0.473 0.000 0.582 0.000 0.347 0.007 0.647 0.000
Spearman’s rho Pinch grip strength 0.371 0.004 0.647 0.000 0.295 0.022 0.555 0.000
Test
Overall hand function (both hands)
China UK
Correlation P-value Correlation P-value
Pearson r Pain (both hands) -0.458 0.000 -0.690 0.000
Spearman’s rho Swelling (both hands) -0.450 0.000 -0.093 0.479
a statistically significant (p?0.05)

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ORCID for Jo Adams: orcid.org/0000-0003-1765-7060

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