1 Hospital Clínic, Rheumatology, Barcelona,
2 Hospital Clínic, Immunology, Barcelona,
3 Hospital Parc Taulí, Rheumatology, Sabadell, Barcelona and
4 Hospital de Granollers, Rheumatology, Granollers, Barcelona, Spain
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Methods. Sixty patients (47 females, 13 males) with RA with a disease duration shorter than 2 yr [mean (S.D.) duration 9.5±6.6 months] were treated with the same therapeutic protocol using gold salts as the first DMARD and methotrexate as a second option, and were followed up for 1 yr. Radiographic progression in the hands and feet (total radiographic Larsen score and the erosion joint count) was used as the outcome variable. Clinical, laboratory, immunogenetic and radiographic data were obtained at study entry. Disease activity and response to therapy were measured at 6 and 12 months.
Results. Erosive disease was found in 21.7% of patients at baseline and in 38.3% after 1 yr. Although a substantial reduction in disease activity was observed during the 1 yr follow-up [disease activity score (DAS28) 5.8±0.8 at entry and 3.9±1.3 at 12 months, P < 0.001], the Larsen score rose from 1.9±3.3 to 5.6±9.8 after 1 yr. In 26.6% of patients, a raised erosion joint count was observed after 1 yr. Radiographic progression in the total joint radiographic damage (increase in Larsen score of 2) was observed in 36.6%. In the multivariate analysis, baseline pain [visual analogue scale (VAS)] and the presence of two copies of the shared epitope were associated with radiographic progression in the erosion joint count. Disease duration before study entry, VAS pain and Larsen score at baseline were significant predictors of radiographic progression in total damage (Larsen score). Baseline radiographic damage had the highest positive predictive value for progression.
Conclusions. Radiographic progression was observed in up to 36.6% of patients with early RA after 1 yr of DMARD therapy in spite of a significant reduction in disease activity. Baseline factors, such as VAS pain, disease duration until DMARD therapy, damage score at baseline and the presence of two copies of the shared epitope, were associated with radiographic progression.
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Although initial factors, such as rheumatoid factor [6, 810], are associated with a poor radiographic outcome in almost all early RA series, others, such as the HLA-DRB1 genotype [11] and elevated inflammatory activity at baseline [12], remain controversial.
Progression of joint damage in Mediterranean countries [9], where the course of the disease may be more benign [13], has been little studied. We evaluated the frequency and baseline prognostic factors of radiographic progression in Spanish early RA patients after 1 yr of treatment with a therapeutic DMARD (disease-modifying anti-rheumatic drug) protocol.
![]() |
Patients and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
All patients underwent clinical examination at baseline and at 3, 6, 9 and 12 months. At baseline we recorded demographic characteristics, disease duration, serum rheumatoid factor, measured by nephelometry, antikeratin antibodies (AKA), measured by indirect immunofluorescence in rat oesophagus [15], anti-cyclic citrullinated peptide antibodies (CCP), measured by ELISA (enzyme-linked immunosorbent assay) [16] and DRB1 genotype, determined by direct DNA sequencing. At baseline and 6 and 12 months, we recorded the level of pain measured with a visual analogue scale (VAS), the 28 tender and swollen joint count, patient and physician assessments of disease status on a Likert scale, the 28-joint disease activity score (DAS28), functional status by the modified Health Assessment Questionnaire (mHAQ) [17], erythrocyte sedimentation rate and C-reactive protein.
Baseline and 12-month hand and foot radiographs were obtained and graded by the LarsenScott method [18]. Thirty-two joints were assessed: bilateral thumb interphalangeal (IP) joints, PIP joints 25, MCP joints 15, IP big toe joints, metatarsophalangeal joints 25 and wrists. Each wrist was considered a unit and its score was multiplied by 5. Thus, the Larsen score ranged from 0 to 200. An erosion joint count (EJC) was made, defined as the number of joints with any evidence of cortical erosion out of 32 joints. All radiographs were read by the same observer (RS) chronologically. As a measure of radiographic progression, we used the minimal clinically important difference (MCID) [19], which was a change of 2 Larsen score units between baseline and 12 months. Any increase (one or more joints with erosions) in the EJC was also considered indicative of radiographic progression.
All patients underwent a therapeutic protocol including gold salts (intramuscular sodium aurothiomalate 50 mg/week) as the first-choice DMARD together with methylprednisolone 4 mg/day. NSAIDs (non-steroidal anti-inflammatory drugs), preferentially indometacin and intra-articular steroid therapy with triamcinolone hexacetonide or acetonide, were used according to clinical judgement. Therapy response was evaluated at 6 and 12 months. Methotrexate at an increasing weekly dose of 7.520 mg was instituted as DMARD monotherapy if adverse effects without clinical improvement or no ACR20 response was observed at 6 months. If a patient had an ACR50 response, including clinical remission, gold salts were scheduled every 23 weeks; if a patient had an ACR20 response but no ACR50 response, combination therapy with gold salts and methotrexate was initiated. Methylprednisolone therapy was tapered according to clinical judgement.
Statistical analysis
Outcome measures were radiographic progression measured separately by the EJC and Larsen score. The univariate analysis of categorical variables used the 2 test or Pearson's exact test, and continuous variables were assessed with Student's t-test, or the MannWhitney test if normality was hard to assume. For paired samples, the t-test, Wilcoxon or McNemar tests were used. Pearson or Spearman correlations were calculated. Marginally significant variables (P<0.15) in the univariate analysis were included in a logistic regression model and removed if the likelihood did not decrease significantly and remaining coefficients did not change by <15%.
All two-level interactions were tested. Intra-observer agreement in Larsen score was assessed with the statistic [20] on 25 randomly chosen pairs of hand and feet radiographs, with a
value of 0.77 [95% confidence interval (CI) 0.610.93]. Positive predictive values of baseline values were calculated to detect radiographic progression in Larsen score, and continuous values were transformed into categorical variables using median values as cut-off points.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
Factors predictive of Larsen radiographic progression
Baseline variables significantly associated with radiological progression in Larsen score in the univariate analysis were VAS pain (P=0.019) and Larsen score (P=0.039). A non-significant trend was observed with disease duration, mHAQ, shared epitope homozygosity and DRB04 alleles. The absence of complete remission at month 6 (P=0.02) and the tender joint count at month 12 (P=0.02) were significantly associated with radiographic progression. Baseline radiographic damage measured by EJC and Larsen scores had the highest positive predictive value for radiographic progression (61.5 and 60.9% respectively) (Table 2). A non-significant trend in radiographic progression was observed in patients without ACR20 and ACR50 responses. No differences were observed between progressors and non-progressors in daily cumulative dose of methylprednisolone or the number of days with
4 mg methylprednisolone (3.5±2.3 mg/day vs 3.2±1.7 and 257.7±147.7 days vs 241.6±124 respectively; not significant). In the multiple regression analysis, disease duration [odds ratio (OR) 1.15, 95% CI 1.031.28], VAS pain at entry (OR 1.02, 95% CI 1.021.09) and Larsen score at entry (OR 1.06, 95% CI 1.061.55) were independent factors associated with total radiographic progression.
|
Factors predictive of EJC progression
Shared epitope homozygosity was observed in 42.9% of patients with EJC radiographic progression and in 15% without (OR 4.25, 95% CI 1.116.7, P=0.038). HLA-DRB04 alleles (71.4 vs 42.5%, P=0.07) and VAS pain at baseline (59.2±23.4 vs 48±21.2, P=0.08) showed a clear non-significant trend of association. In the regression analysis, shared epitope homozygosity (OR 5.7, 95% CI 1.125.9) and VAS pain at entry (OR 1.02, 95% CI 11.07) were associated with EJC progression.
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Radiographic progression at 1 yr was found in a significant proportion of patients: in 26.6% when the criterion was a raised EJC and in 36.6% when it was a 2-unit change in Larsen score. Some prospective studies of radiographic damage and predictive factors of joint damage at 1 yr in early RA patients have analysed radiographic damage or erosions at the end of follow-up rather than radiographic progression [8, 25, 26]. This study used the MCID, which is recommended when using the LarsenScott method to measure 1 yr progression in early RA patients [19], and to our knowledge this is the first study of prognostic factors in early RA to do so.
As we used two separate criteria to define radiographic progression, thus identifying similar but not equal populations, it is not surprising that some variables predict radiological progression using one criterion but not the other. For example, homozygosity for the shared epitope was a predictor of progression measured by the appearance of new erosions, and a clear trend was also observed in HLA-DRB04 alleles containing the rheumatoid epitope. By contrast, none of these immunogenetic markers was significantly associated with progression when total Larsen score was the measure of damage progression. Whether immunogenetic traits predict erosive disease rather than more severe structural damage is difficult to ascertain. The exact role of DRB1 genes in the severity of RA remains controversial, some reports showing more substantial radiographic joint damage with DRB04 alleles, in particular with genotypes homozygous for the shared epitope [26, 27], and others finding no relationship with the severity of radiographic damage [28] or finding it only in patients with seronegative disease [29]. However, a recent report suggests that early DMARD therapy may modify the association between DRB1 genotype and disease severity [30].
Rheumatoid factor, a powerful predictor of joint damage in early RA [1, 6, 8, 11, 13], was not associated with radiographic progression in our study, although the number of seronegative cases was small, and a type II error due to insufficient sample size cannot be excluded. Rheumatoid factor positivity after 1 yr of DMARD therapy (not analysed in this study) may predict radiographic progression better than seropositivity at entry [31]. Furthermore, some of our seronegative patients may become rheumatoid factor-positive during follow-up. Neither AKA nor anti-CCP antibodies were associated with radiographic progression in our study, as in other reports [9], although an independent association of erosions in early RA with these antibodies has been reported [32].
Disease duration until DMARD therapy was associated with progression of total damage score. Although this could be influenced by a worse radiographic score at study entry, a known factor predicting radiographic progression [3, 6, 9], as in this study, regression analysis showed that disease duration was an independent factor. However, as in the 3 yr prospective study of radiographic progression in early RA by Combe et al. [9], baseline radiographic damage emerged as one of the most important markers of radiographic progression, with the highest positive predictive values (about 60%) in our study.
Unlike comparable studies, all patients received a structured therapeutic regimen using gold salts as the first DMARD, and methotrexate in monotherapy or in combination with gold salts if patients were unresponsive or suffered adverse events. Both drugs cause significant slowing of radiographic damage in RA patients, with no differences between them at 1 and 3 yr of follow-up [33, 34]. However, most patients received low-dose corticosteroids, which could contribute to reduced radiographic progression [35], although no association between accumulated methylprednisolone doses and radiographic progression was observed in our study.
In several studies, disease activity measured by clinical or laboratory parameters at study entry or as a time-integrated value [36, 37] correlated with structural damage, although this was not the case in other surveys [38]. Multivariate analysis identified no factor related to disease activity at baseline or response to therapy during the follow-up period in our study. However, in the univariate analysis, the absence of complete remission at month 6 and a high 1 yr tender joint count was associated with radiographic progression. This probably reflects the fact that both baseline factors and the effects of DMARD therapy on inflammation play a role in structural damage, although the complex interrelationship between these variables is not well understood.
Limitations of the present study include the relatively small sample size, which could mean that the associations with some variables were weaker than they really are. Furthermore, as a significant proportion of patients may develop radiographic progression or new erosions after the second year of disease [39], the results, especially at 1 yr, should be interpreted cautiously. However, the positive predictive values of the baseline variables for progression were mostly lower than 50%, limiting their individual value as progression markers.
In conclusion, in one-third of patients with early RA who were treated with DMARDs, a significant increase in radiographic damage was found after 1 yr of follow-up. Several baseline factors, such as VAS pain, radiographic damage, disease duration and immunogenetic traits, were found to be predictors of progression. Whether these factors can predict structural damage in the long term, and thus warrant more aggressive therapeutic approaches, remains to be determined.
![]() |
Acknowledgments |
---|
![]() |
Notes |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|