Research Report
Age-related diagnostic utility of rheumatoid factor, anticyclic citrullinated peptide and antikeratin antibodies in Chinese patients with rheumatoid arthritis
Journal of International Medical Research 2014, Vol. 42(3) 711–717 ! The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0300060514524734 imr.sagepub.com
Jinpiao Lin1,2, Can Liu1,2, Bin Yang1,2 and Qishui Ou1,2
Abstract Objectives: Retrospective study to evaluate the diagnostic utility of rheumatoid factor (RF), anticyclic citrullinated peptide antibodies (ACPA) and antikeratin antibodies (AKA) in a broad age range of patients with rheumatoid arthritis (RA). Methods: Clinical and serological data from patients with RA were collected and analysed. Patients were stratified according to age (60 years) and sex. Results: The study included 3725 patients. There were no significant sex-related differences in rates of RF, ACPA or AKA positivity. RF, ACPA and AKA positivity were significantly less common in patients aged 5 RU/ml were considered positive. An AKA titre >1 : 10 was considered positive. Serum RF was quantified by immunoturbidimetric assay (Dade Behring, Marburg, Germany), with values 10 IU/ml considered positive.
Statistical analyses Data were presented as mean SD or n (%) and stratified according to sex or age (aged 60 years). Between-group comparisons were made using 2-test, and odds ratios (OR) with 95% confidence intervals (95% CI) were calculated. Data analyses were performed using IBM SPSSÕ version 21.0 (IBM SPSS, Tokyo, Japan). P-values 1 : 10.
respectively; Table 3). There were no other significant between-group differences.
Discussion A considerable portion of the disability in early stage and established RA is due to joint damage;17 early diagnosis and prevention of such damage is therefore a major treatment goal. IdentiEcation of reliable disease predictors may enable modification of the disease course. Several serological biomarkers for RA (including ACPA, RF and AKA) have been evaluated,18 and the findings of the present study indicate that these laboratory variables differ between JIA and adult RA. Juvenile idiopathic arthritis is an umbrella term used to indicate a childhood-onset disease, characterized primarily by arthritis of unknown aetiology, which persists for 6 weeks.19 The development of JIA is influenced by gene–gene interactions20 and the Th1/Th2 pathway.21 The present finding that RF-, ACPA- and AKApositive status was significantly lower in patients aged 60 years. RF levels are elevated in 75% of patients with RA and this analysis is widely used for diagnosis.25 ACPA positivity is frequently observed in patients with RA, especially in early disease,26,27 and has a specificity approaching 100% for RA diagnosis.28 The sensitivities of RF, ACPA and AKA in patients aged >16 years in the present study were 80.1%, 78.2% and 29.1%, respectively, and there
Downloaded from imr.sagepub.com at University of Southern Queensland on March 15, 2015
20 (42.6)
16 15 (93.8)
1 (6.3)
AKA, n Negative
Positive
Downloaded from imr.sagepub.com at University of Southern Queensland on March 15, 2015
37 (24.0)
154 117 (76.0)
468 (79.1)
120 (30.2)
398 278 (69.8)
1114 (78.5)
1420 306 (21.5)
Data presented as n or n (%). OR: odds ratio; 95% CI: 95% confidence interval. RF positive, 10 IU/ml; ACPA positive, >5 RU/ml; AKA positive, titre >1 : 10.
204 (29.1)
702 498 (70.9)
1945 (78.2)
592 124 (20.9)
47 (31.3)
150 103 (68.7)
363 (76.4)
475 112 (23.6)
542 (78.8)
1.24)
46.82)
0.37)
8.70)
0.27)
8.71)
Positive
2487 542 (21.8)
1696 (80.9)
– 5.67 (3.69, P < 0.001a 0.18 (0.11, P < 0.001a – 4.84 (2.70, P < 0.001a 0.21 (0.11, P < 0.001a – 6.14 (0.81, P ¼ 0.08a 0.16 (0.02, P ¼ 0.08a
47 27 (57.4)
676 (79.3)
688 146 (21.2)
ACPA, n Negative
2914 (80.1)
2096 400 (19.1)
37 (41.6)
852 176 (20.7)
Positive
3636 722 (19.9)
89 52 (58.4)
RF, n Negative
>60
Age-related diagnostic utility of rheumatoid factor, anticyclic citrullinated peptide and antikeratin antibodies in Chinese patients with rheumatoid arthritis
Journal of International Medical Research 2014, Vol. 42(3) 711–717 ! The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0300060514524734 imr.sagepub.com
Jinpiao Lin1,2, Can Liu1,2, Bin Yang1,2 and Qishui Ou1,2
Abstract Objectives: Retrospective study to evaluate the diagnostic utility of rheumatoid factor (RF), anticyclic citrullinated peptide antibodies (ACPA) and antikeratin antibodies (AKA) in a broad age range of patients with rheumatoid arthritis (RA). Methods: Clinical and serological data from patients with RA were collected and analysed. Patients were stratified according to age (60 years) and sex. Results: The study included 3725 patients. There were no significant sex-related differences in rates of RF, ACPA or AKA positivity. RF, ACPA and AKA positivity were significantly less common in patients aged 5 RU/ml were considered positive. An AKA titre >1 : 10 was considered positive. Serum RF was quantified by immunoturbidimetric assay (Dade Behring, Marburg, Germany), with values 10 IU/ml considered positive.
Statistical analyses Data were presented as mean SD or n (%) and stratified according to sex or age (aged 60 years). Between-group comparisons were made using 2-test, and odds ratios (OR) with 95% confidence intervals (95% CI) were calculated. Data analyses were performed using IBM SPSSÕ version 21.0 (IBM SPSS, Tokyo, Japan). P-values 1 : 10.
respectively; Table 3). There were no other significant between-group differences.
Discussion A considerable portion of the disability in early stage and established RA is due to joint damage;17 early diagnosis and prevention of such damage is therefore a major treatment goal. IdentiEcation of reliable disease predictors may enable modification of the disease course. Several serological biomarkers for RA (including ACPA, RF and AKA) have been evaluated,18 and the findings of the present study indicate that these laboratory variables differ between JIA and adult RA. Juvenile idiopathic arthritis is an umbrella term used to indicate a childhood-onset disease, characterized primarily by arthritis of unknown aetiology, which persists for 6 weeks.19 The development of JIA is influenced by gene–gene interactions20 and the Th1/Th2 pathway.21 The present finding that RF-, ACPA- and AKApositive status was significantly lower in patients aged 60 years. RF levels are elevated in 75% of patients with RA and this analysis is widely used for diagnosis.25 ACPA positivity is frequently observed in patients with RA, especially in early disease,26,27 and has a specificity approaching 100% for RA diagnosis.28 The sensitivities of RF, ACPA and AKA in patients aged >16 years in the present study were 80.1%, 78.2% and 29.1%, respectively, and there
Downloaded from imr.sagepub.com at University of Southern Queensland on March 15, 2015
20 (42.6)
16 15 (93.8)
1 (6.3)
AKA, n Negative
Positive
Downloaded from imr.sagepub.com at University of Southern Queensland on March 15, 2015
37 (24.0)
154 117 (76.0)
468 (79.1)
120 (30.2)
398 278 (69.8)
1114 (78.5)
1420 306 (21.5)
Data presented as n or n (%). OR: odds ratio; 95% CI: 95% confidence interval. RF positive, 10 IU/ml; ACPA positive, >5 RU/ml; AKA positive, titre >1 : 10.
204 (29.1)
702 498 (70.9)
1945 (78.2)
592 124 (20.9)
47 (31.3)
150 103 (68.7)
363 (76.4)
475 112 (23.6)
542 (78.8)
1.24)
46.82)
0.37)
8.70)
0.27)
8.71)
Positive
2487 542 (21.8)
1696 (80.9)
– 5.67 (3.69, P < 0.001a 0.18 (0.11, P < 0.001a – 4.84 (2.70, P < 0.001a 0.21 (0.11, P < 0.001a – 6.14 (0.81, P ¼ 0.08a 0.16 (0.02, P ¼ 0.08a
47 27 (57.4)
676 (79.3)
688 146 (21.2)
ACPA, n Negative
2914 (80.1)
2096 400 (19.1)
37 (41.6)
852 176 (20.7)
Positive
3636 722 (19.9)
89 52 (58.4)
RF, n Negative
>60
