RESEARCH - Sparing of the thumb in Raynaud's phenomenon

January 23, 2008

Rheumatology 2008 47(2):219-221; doi:10.1093/rheumatology/kem353

Sparing of the thumb in Raynaud's phenomenon

B. Chikura1, T. L. 2, J. B. Manning2, A. Vail3 and A. L. Herrick2

1The Royal Liverpool University Hospital, Liverpool, 2Rheumatic

Diseases Centre and 3Biostatistics Group, University of Manchester,

Hope Hospital, Salford, UK.

Abstract

Objectives. To conduct a prospective study to determine which digits

are affected (and whether the thumb is spared or not) in a cohort of

patients with RP as assessed by symptoms and thermography and to

determine whether the degree of thumb involvement differs between

primary (PRP) and secondary Raynaud's phenomenon (SRP).

Methods. This was a cross-sectional study of 44 patients with RP. The

following characteristics were recorded to allow comparisons between

digits: symptoms of RP in each digit (graded on a scale of 'never',

'sometimes' and 'always' affected during an attack of RP) and

thermography at 23°C. A distal–dorsal difference (DDD) in temperature

at 23°C of –1°C or less was considered to be clinically relevant.

Results. Symptom scores in the thumb were significantly better, i.e.

less severe than in each finger (P < 0.001). As only three

participants had any finger better than the thumb, there was no power

to compare whether the thumb was spared more in PRP compared with SRP.

Mean DDD was significantly higher (i.e. better) in the thumb compared

with each finger (P < 0.001). Although DDD scores were higher in PRP

compared with SRP (P = 0.01), there was no evidence that the relative

effect of the thumb differed between the two groups (P = 0.26).

Conclusions. Our findings confirm that the thumbs are spared in RP,

both primary and secondary, as demonstrated by both symptoms and

thermography. The reasons for sparing of the thumb were not addressed

in this study but raised questions regarding pathophysiolgy.

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Not an MD

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