Table 2

Risk factors associated with the development of incident gangrene during the observation period

Risk factorIncident gangrene n/N (%)No incident gangrene, n/N (%)OR (95% CI)p Value*
(A) ULR (N=3809)N=243N=3566
Female gender189/243 (77.8)2938/3566 (82.4)0.73 (0.53 to 1.01)0.055
Smoking status
 Current45/205 (22.0)438/3102 (14.1)1.91 (1.32 to 2.76)<0.001
 Former58/205 (28.3)728/3102 (23.5)1.46 (1.04 to 2.04)0.028
Number of finger DUs at enrolment
 1–289/236 (37.7)1315/3546 (37.1)1.27 (0.93 to 1.72)0.132
 3+58/236 (24.6)666/3546 (18.8)1.54 (1.09 to 2.17)0.015
Anti-Scl 70103/196 (52.6)1279/2872 (44.5)1.39 (1.04 to 1.87)0.027
Previous gangrene96/229 (41.9)404/3378 (12.0)4.75 (3.57 to 6.34)<0.0001
Previous autoamputation32/231 (13.9)188/3386 (5.6)2.69 (1.78 to 4.04)<0.0001
Previous soft-tissue infection requiring systemic antibiotics94/222 (42.3)933/3253 (28.7)1.76 (1.33 to 2.32)<0.0001
Previous osteomyelitis19/232 (8.2)84/3367 (2.5)3.24 (1.19 to 5.47)<0.0001
Ongoing autoamputation6/242 (2.5)46/3552 (1.3)2.32 (0.97 to 5.57)0.059
Ongoing osteomyelitis4/243 (1.6)24/3558 (0.7)2.36 (0.80 to 6.99)0.121
Previous hospitalisation(s) for DUs (at least 1 day)144/231 (62.3)1290/3385 (38.1)2.49 (1.89 to 3.29)<0.0001
Previous upper limb sympathectomy20/228 (8.8)100/3345 (3.0)3.24 (1.94 to 5.40)<0.0001
Previous digital sympathectomy11/228 (4.8)58/3341 (1.7)2.70 (1.38 to 5.31)0.004
Previous arterial reconstruction5/227 (2.2)21/3336 (0.6)3.43 (1.25 to 9.44)0.017
Not employed/self-employed205/243 (84.4)2687/3566 (75.4)1.78 (1.22 to 2.61)0.003
(B) MLR(N=2479)N=157N=2322
Observation time, mean (SD), weeks174.7 (78.7)126.2 (78.9)1.03 (1.02 to 1.04)<0.0001
Smoking status
 Current27/157 (17.2)311/2322 (13.4)1.72 (1.07 to 2.77)0.025
 Former47/157 (29.9)509/2322 (21.9)1.69 (1.14 to 2.51)0.009
Number of finger DUs at enrolment
 1–260/157 (38.2)951/2322 (41.0)1.35 (0.90 to 2.03)0.144
 3+46/157 (29.3)491/2322 (21.1)1.69 (1.09 to 2.62)0.020
Anti-Scl 7079/157 (50.3)1031/2322 (44.4)1.39 (0.99 to 1.96)0.058
Previous gangrene63/157 (40.1)244/2322 (10.5)4.67 (3.24 to 6.73)<0.0001
Previous upper limb sympathectomy15/157 (9.6)67/2322 (2.9)2.21 (1.15 to 4.27)0.018
  • *Wald χ2 test.

  • For the ULR analysis, observation time was a fixed covariate in the model. Data are shown for variables having p<0.15 and n>3000 for the patients for whom information is available).

  • For the MLR analysis, observation time was forced into the model as a fixed covariate and not included by the forward selection procedure; variables were selected with a selection criterion of p=0.15. Data are shown for the subset of patients making up the final models (n=2479) to allow comparison with the full cohort.

  • ACA, anticentromere antibody; ANA, antinuclear antibody; DU, digital ulcer; MLR, multivariable logistic regression; PAH, pulmonary arterial hypertension; RNP, ribonucleic protein; ULR, univariable logistic regression.