Association of Improvement in Pain With Therapeutic Response as Determined by Individual Improvement Criteria in Patients With Rheumatoid Arthritis

Objective

To use statistical methods to establish a threshold for individual response in patient‐reported outcomes (PROs) in patients with rheumatoid arthritis.

Methods

We used an analysis of variance model in patients on stable therapy (discovery cohort) to establish critical differences (d_crit) for the minimum change associated with a significant individual patient response (beyond normal variation) in the PRO measures of pain (0–10), fatigue (0–10), and function (Funktionsfragebogen Hannover questionnaire; 0–100). We then evaluated PRO responses in patients initiating adalimumab in a noninterventional study (treatment cohort).

Results

In the discovery cohort (n = 700), PROs showed excellent long‐term retest reliability. The minimum change that exceeded random fluctuation was conservatively determined to be 3 points for pain, 4 points for fatigue, and 16 points for function. In the treatment cohort (n = 2,788), 1,483 patients (53.2%) achieved a significant individual therapeutic response as assessed by Disease Activity Score in 28 joints (DAS28)–d_crit (≥1.8 points) after 12 months of adalimumab treatment; 68.5% of patients with a DAS28‐d_crit response achieved a significant improvement in pain, whereas approximately 40% achieved significant improvements in fatigue or function. Significant improvements in all 3 PROs occurred in 22.7% of patients; 22.8% did not have any significant PRO responses. In contrast, significant improvements in all 3 PROs occurred in only 4.4% of 1,305 patients who did not achieve a DAS28‐d_crit response at month 12, and 59.1% did not achieve any significant PRO responses.

Conclusion

The establishment of critical differences in PROs distinguishes true responses from random variation and provides insights into appropriate patient management.

Development and validation of a new disease activity score in 28 joints-based treatment response criterion for rheumatoid arthritis

OBJECTIVE

To define a valid criterion for treatment response as assessed by the Disease Activity Score in 28 joints (DAS28) that exceeds random disease activity variations in patients with rheumatoid arthritis (RA).

METHODS

We utilized anonymized data sets of RA patients from multiple rheumatology centers in Germany to identify patients with stable responses to conventional or biologic disease-modifying antirheumatic drug (DMARD) therapy (discovery cohort). To evaluate fluctuations in DAS28 scores, we subjected patients' DAS28 scores at months 12, 18, and 24 to an analysis of variance model to establish a 1-sided 95% confidence interval for normal fluctuations; this value was used to define the critical difference (DAS28-dcrit ) for individual changes from baseline. The DAS28-dcrit value was then applied to analyses of therapeutic response in an adalimumab noninterventional study cohort.

RESULTS

The discovery cohort included 415 patients receiving stable treatment. Values for DAS28-dcrit were comparable regardless of age, sex, disease activity, and class of therapy (DMARDs or biologic agents) and fell below 1.8 in all subgroups. We therefore conclude that DAS28 improvements of 1.8 or higher are outside the normal variation and represent a therapeutic response. When applied to data from the adalimumab noninterventional study (n = 1,874), a DAS28-dcrit response was more robust over time than a European League Against Rheumatism response and was more closely correlated with improved functional capacity.

CONCLUSION

Based on our data, a DAS28-dcrit value of 1.8 signifies a positive individual therapeutic response that exceeds the threshold of random fluctuation. The DAS28-dcrit criterion may be useful in steering individual therapy and stratifying clinical trials.

The German national registry for primary immunodeficiencies (PID)

In 2009, a federally funded clinical and research consortium (PID-NET, http://www.pid-net.org) established the first national registry for primary immunodeficiencies (PID) in Germany. The registry contains clinical and genetic information on PID patients and is set up within the framework of the existing European Database for Primary Immunodeficiencies, run by the European Society for Primary Immunodeficiencies. Following the example of other national registries, a central data entry clerk has been employed to support data entry at the participating centres. Regulations for ethics approvals have presented a major challenge for participation of individual centres and have led to a delay in data entry in some cases. Data on 630 patients, entered into the European registry between 2004 and 2009, were incorporated into the national registry. From April 2009 to March 2012, the number of contributing centres increased from seven to 21 and 738 additional patients were reported, leading to a total number of 1368 patients, of whom 1232 were alive. The age distribution of living patients differs significantly by gender, with twice as many males than females among children, but 15% more women than men in the age group 30 years and older. The diagnostic delay between onset of symptoms and diagnosis has decreased for some PID over the past 20 years, but remains particularly high at a median of 4 years in common variable immunodeficiency (CVID), the most prevalent PID.