Clinical utility of serum concentrations of adalimumab as predictor of treatment adherence

Objective: to evaluate the usefulness of serum concentrations (Sc) of adalimumab (ADA) as a predictor of medication adherence using the medication possession ratio (MPR) and Morisky Green test (MGT) in patients with chronic inflammatory diseases.

Material and method: Design a prospective descriptive cohort study.

Inclusion criteria: adult patients diagnosed with inflammatory arthropathy (IA) or inflammatory bowel disease (IBD) treated with ADA.

Exclusion criteria: positive anti-adalimumab antibody.

Variables: sex, age, diagnosis, dosage regimen, Sc (mg/mL), MPR (MPR ≥ 80% adherent) and MGT (non-adherent or adherent). Statistical analysis was performed using STATA v13.0.

Results: Forty-five patients (23 women) with an age of 52.22 (14.39) years, 17 IBD (37.78%), 26 IA (57.78%) and 2 with both conditions (4.44%) treated with 40mg ADA every 14 days (42/45; 93.33%) or every 7 days (3/45; 6.67%). We detected subtherapeutic Sc in 22.22% of patients (10/45); 10% (1/10) were classified as non-adherent and 90% (9/10) as adherent according to MGT and MPR. The quantification of Sc shows weak agreement with MPR, as was the case with the indirect methods of each (MPR and MGT). The association was slightly greater when the indirect methods were compared to each other (0.244 vs. 0.378).

Conclusion: the determination of Sc of ADA alone has limited utility in the detection of non-adherent patients.