I don’t know what type of arthritis I have: A population-based comparison of people with arthritis who knew their specific type and those who didn’t

Objective

To understand differences between people with arthritis who do not know their type (DK) compared to those reporting osteoarthritis (OA) or inflammatory and autoimmune types of arthritis (IAA), including the receipt of appropriate health care, information, and services.

Methods

Analysis of the Survey on Living with Chronic Disease in Canada–Arthritis Component. Respondents aged ≥20 years with health professional-diagnosed arthritis (n = 4,385) were characterized as reporting DK, OA or IAA. Variables: arthritis characteristics (duration, number and site of joints affected), arthritis impact (current pain and fatigue, difficulty in sleeping and daily activities, impact on life), health (self-rated general and mental health, life stress), arthritis management strategies (seeing health professionals, medication use, assistive devices, receipt of arthritis information, self-management activities). Multinomial logistic and log-Poisson regressions were used, as appropriate, to compare the DK to the OA and IAA groups.

Results

In this arthritis sample, 44.2% were in the DK group, 38.3% reported OA and 17.5% reported IAA. Those in the DK group were more likely to be younger, have low income, low education, and be of non-white cultural background compared to those with OA. There were no significant differences in arthritis impact, but the DK group was less likely to have received information on, or have used, arthritis management strategies.

Conclusions

The sociodemographic characteristics of the DK group suggest they likely have lower health literacy. They were less likely to have accessed health care and other support services, indicating this is an important group for health education, both for individuals with arthritis and health care providers.

A whole-joint, unidimensional, irreversible, and fine-grained MRI knee osteoarthritis severity score, based on cartilage, osteophytes and meniscus (OA-COM)

Objective

To develop a whole-joint, unidimensional, irreversible, and fine-grained MRI knee osteoarthritis (OA) severity score, based on cartilage, osteophytes and meniscus (OA-COM), and to predict progression across different severity states using OA-COM as outcome and clinical variables as predictors.

Methods

Population-based knee pain cohort aged 40–79 was assessed at baseline and 7-year follow-up. OA-COM score was defined as the sum of MRI scores for cartilage, osteophytes and menisci, measured at 6, 8 and 6 sites, total score 0–54. To anchor severity levels, we fit cross-sectional logistic models using OA-COM to predict Kellgren-Lawrence (KL) grades in subsets at or one point below each grade. OA-COM threshold scores were selected on sensitivity, specificity, positive and negative predictive value. We developed longitudinal logistic models for OA-COM progression over each threshold over 7 years. Potential predictors included age, sex, BMI, malalignment, physical exam effusion, quadriceps weakness, and crepitus, selected on area under the receiver operating characteristic curve (AUC) and Akaike’s Information Criterion (AIC).

Results

Optimal OA-COM thresholds were 12, 18, 24 and 30, for KL grades 1 to 4. Significant predictors of progression (depending on threshold) included physical exam effusion, malalignment and female sex, with other selected predictors age, BMI and crepitus.

Conclusion

OA-COM (0–54 range) is a whole-joint, unidimensional, irreversible, and fine-grained MRI OA severity score reflecting cartilage, osteophytes and menisci. OA-COM scores 12, 18, 24 and 30 are equivalent to KL grades 1 to 4, while offering fine-grained differentiation of states between KL grades, and within pre-radiographic disease (KL = 0) or late-stage disease (KL = 4). In modeling, several clinical variables predicted progression across different states over 7 years.

Adenosine deaminase 2 activity negatively correlates with age during childhood

BACKGROUND

Human adenosine deaminase 2 (ADA2) is an extracellular enzyme that negatively regulates adenosine-mediated cell signaling by converting adenosine to inosine. Altered ADA2 enzyme activity has been associated with some viral infections and rheumatic diseases. The potential utility of ADA2 as a biomarker is, however, limited by the absence of established ranges of ADA2 concentration and enzyme activity in the healthy population. It is known that ADA2 enzyme activity is lower in adults, but when (and why) this decline happens is not known. The purpose of this study was to establish normative ranges of ADA2 enzyme activity and protein concentration in the healthy pediatric population.

METHODS

We modified a commercially available ADA2 enzyme activity assay to enable higher throughput analysis of fresh, frozen and hemolyzed blood samples. With this assay and ADA2 protein immunoblotting, we analyzed ADA2 enzyme activity and protein concentration in blood plasma from a cohort of children and adolescents (n = 94) aged 5 months to 18 years. One-way ANOVA with subsequent Tukey multiple comparison test was used to analyze group differences. Reference intervals were generated using the central 95% of the population (2-97.5 percentiles).

RESULTS

ADA2 enzyme activity was consistent in fresh, frozen, and hemolyzed sera and plasma as measured by our modified assay. Analysis of plasma samples from the healthy pediatric cohort revealed that ADA2 enzyme activity is significantly lower in older children than in younger children (p < 0.0001). In contrast, there was no significant correlation between ADA2 protein concentration and either age or ADA2 enzyme activity.

CONCLUSION

We observed that ADA2 enzyme activity, but not ADA2 protein concentration, negatively correlates with age in a cohort of children and adolescents. Our findings stress the importance of appropriate age-matched controls for assessing ADA2 enzyme activity in the clinical setting.