Data from 126 individuals with RA were analyzed giving a catchment of 54%. The 110 RA patients who declined to participate in the study were older (74 vs. 70, p=0.0001), had a higher mean erythrocyte sedimentation rate (ESR) (27 vs. 19, p=0.0001), had a higher mean DAS28ESR (Disease Activity Score using ESR) (3.4 vs. 3.0, p=0.005) and were less often on biologics (7% vs. 22%, p=0.003), but did not otherwise differ from the RA patients included in the study. A total of 83% of the RA patients fulfilled the 1987 ACR classification criteria and 71% the 2010 ACR/EULAR classification criteria for RA. The period prevalence of RA was 1.5%.
Demographics and health characteristics of the study population
Demographics and health characteristics of the study population are summarized in Table 1.
All study individuals in the RA group were born in Sweden. The study group with a diagnosis of RA included more women than in the control group (p<0.01). The mean BMI was higher in the RA group (p<0.001). Interstitial lung disease was more common in individuals with RA (p=0.002). Analyses failed to demonstrate study group difference by socio-economic status (SES) (p=0.72), or for a history of smoking (p=0.58). The age matching criteria were successful in recruiting individuals of similar ages (both with a mean value of 70 years) for the two study groups (p=0.39).
Rheumatoid arthritis
Table 2 describes the disease activity assessments, and antirheumatic medications for the study individuals with RA. Among the individuals with RA, 66% were on DMARDs (disease-modifying antirheumatic drugs), 57% were using methotrexate, 22% were using biologics and 45% were medicated with glucocorticoids. A majority of the individuals in the RA group (63%) were in remission or diagnosed as having low disease activity. Using ≥ 25 U/mL anti- CCP-2 (antibodies against citrullinated proteins) analysis in serum, 66% of the study individuals were positive.
Findings from the dental examination
Data from the dental examination are presented in Table 3. Radiographic evidence of bone loss (distance between CEJ to bone ≥ 5 mm) was more common in the RA-group (p=0.03). The number of remaining teeth was higher in the control group (p=0.001). No significant group differences were, however, found for the number of sites with a PPD value ≥ 5 mm, BOP, or plaque scores, the number of root remnants, or peri-apical lesions. Data analyses were also unable to show group differences for the number of teeth with open carious lesions (p=0.30), or for the number of dental implants present. In addition, no group differences were found regarding the number of dental visits per year (94 % vs 90 %, P=0.30). A dental diagnosis of periodontitis based on the composite periodontal index was higher in the RA group (p<0.001).
Subset analysis of periodontal conditions by gender among individuals in the RA group
There were no gender differences regarding the number of remaining teeth (p=0.81), the extent of bleeding on probing (p=0.65), the number of tooth sites with a probing depth ≥ 5 mm (p=0.98), or the bone level distance ≥ 5 mm (p=0.75). Also, no gender difference in the presence or absence of periodontitis was found (p=0.92).
Treatment with methotrexate, DMARDs, biologics, glucocorticoids and non-steroidal anti-inflammatory drugs (NSAIDs) had no impact on periodontal conditions (p values varied between 0.70 and 0.95). ). A sub analysis on RA patients with a positive or negative anti-CCP titer was also performed. In this sub analysis no association between anti-CCP positivity and periodontitis was found (p=0.92).
Subset analysis of periodontal conditions by gender among individuals in the control group
There were no gender differences regarding the number of remaining teeth (p=0.49), the extent of bleeding on probing (p=0.65), the number of tooth sites with a probing depth ≥ 5 mm (p=0.12), or the bone level distance ≥ 5 mm (p=0.18). Also, no gender difference in the presence or absence of periodontitis was found (p=0.68).
Analyses by binary backward conditional logistic regression
Based on information from the literature and from the results presented above the following categorical variables were included: gender, acute myocardial infarct, stroke, diabetes (I and II merged), BMI score > 25, white collar or blue collar worker (SES), smoking history (never or anytime), and age. In addition, periodontitis as defined above by the composite index. In the analysis, bleeding on probing was defined as the expression of gingivitis ≥ 20% of sites, probing pocket depth ≥ was defined at 3 sites or more with a PPD score ≥ 5 mm and alveolar bone loss was defined as a distance between CEJ to bone ≥ 5 mm at ≥ 30% of sites.
The following covariates remained in the final analysis; BMI > 25, gender, composite periodontal score (Table 4). Other covariates including age (p=0.80), acute myocardial infarction (p=0.81), stroke (p=0.23), socio-economic status (p=0.77) and smoking status (p=0.73) failed to reach significance.