Ultrasound Doppler enthesitis shows sensitivity to change after biological therapy in spondyloarthritis and psoriatic arthritis patients.

OBJECTIVE: To explore the sensitivity to change in power Doppler (PD) enthesitis in active spondyloarthritis (SpA) and psoriatic arthritis (PsA) patients. METHOD: This was a longitudinal study in patients with SpA and PsA with active disease [patients starting or switching to biological disease-modifying anti-rheumatic drugs (bDMARDs)]. The MAdrid Sonographic Enthesitis Index (MASEI) was performed at baseline and at 3 and 6 month visits. The MASEI and Outcome Measures in Rheumatology (OMERACT) PD enthesitis definitions were checked. Reliability analysis among three readers was performed with ultrasound (US)-recorded videos. RESULTS: US examinations of 25 patients were included; 16 (64%) had SpA and nine (36%) PsA. The median (interquartile range, IQR) age was 49 (41-61) years, and 13 patients (52%) were female. The median (IQR) 28-joint Disease Activity Score of 3.6 (2.3-4.2), Bath Ankylosing Spondylitis Disease Activity Index of 6.7 (6.1-7.4), and C-reactive protein value of 8.2 (1.6-20) reflected moderate to high disease activity at baseline. Both MASEI and OMERACT PD enthesitis improved significantly at 3 and 6 month follow-up (p < 0.05) and showed sensitivity to change (standard error of measurement = 0.47 and 0.61, respectively). Improvement in clinical activity outcomes was significantly associated with decreases in MASEI and OMERACT PD enthesitis counts (p < 0.05). The MASEI and OMERACT PD definitions had excellent reliability (kappa = 0.918 and 0.865, respectively). CONCLUSION: PD enthesitis significantly improved at 3 and 6 month follow-up in patients undergoing bDMARD therapy. Both MASEI and OMERACT PD US enthesitis reflect response to treatment.

Early monitoring of infliximab serum trough levels predicts long-term therapy failure in patients with axial spondyloarthritis.

OBJECTIVE: To evaluate whether serum infliximab trough levels (ITL) during the early stages of treatment are predictive of long-term clinical failure in patients with axial spondyloarthritis (axSpA). METHODS: Longitudinal observational study involving 81 patients with axSpA monitored during infliximab therapy. Serum ITL were measured before starting infliximab treatment and at weeks 2 (W2), W6 and W12 of treatment. Disease activity was assessed by Ankylosing Spondylitis Disease Activity Score (ASDAS) at baseline, W24 and W52, and every 6 months thereafter until treatment discontinuation, regardless of the reason. Non-clinically important improvement was defined by ΔASDAS<1.1. The association between serum levels during the early stages and clinical outcomes (non-clinically important improvement at W52, drug survival and drop-out due to secondary inefficacy) was investigated through logistic regression models and Kaplan Meier curves. Receiver operating characteristic (ROC) curves were employed to determine the best cut-off for serum ITL. RESULTS: Out of the 81 patients, 45 (56%) did not achieve clinical improvement at W52. These patients had lower serum ITL at W12 compared to those who improved: ITL [median (IQR)]: 4.1(0.9-8.3) µg/mL vs 7.1 (4.3-11.3) µg/mL, respectively;p = 0.007). ITL<6.7 µg/mL at W12 was significantly associated with: i) not achieving clinical improvement at W52 (OR: 2.3; 95%CI: 1.3-3.9); ii) shorter drug survival (5.0 years (95% CI 3.8-6.2) vs 7.0 years (95% CI 4.8-6.9; p = 0.04), and iii) higher drop-out rates due to secondary inefficacy (OR: 3.5; 95% CI: 1.2-10.2). CONCLUSION: Low serum ITL at W12 were associated with long-term clinical failure in patients with axSpA, due to secondary inefficacy.

Can we identify individuals with an ALPL variant in adults with persistent hypophosphatasaemia?

BACKGROUND: Hypophosphatasia (HPP) is an inborn error of metabolism characterized by low levels of serum alkaline phosphatase (ALP). Scarce evidence exists about features that should signal the potential association between hypophosphatasaemia and HPP in adults. The aim of this study is to estimate the prevalence of ALPL variants in subjects with persistent hypophosphatasaemia and determine the associated clinical and laboratory features. For this cross-sectional study, laboratory records of 386,353 subjects were screened by measurement of ALP activity. A total of 85 (0.18%) subjects with persistent hypophosphatasaemia (≥2 serum alkaline phosphatase-ALP-measurements ≤35 IU/L and none > 45 IU/L) were included (secondary causes previously discarded). ALPL genetic testing and a systematized questionnaire to retrieve demographic, clinical and laboratory data were performed. Descriptive analysis and logistic regression models were employed to identify the clinical and laboratory characteristics associated with ALPL variants. RESULTS: Forty subjects (47%) had a variant(s) in ALPL. With regard to clinical characteristics, the presence of an ALPL variant was significantly associated only with musculoskeletal pain (OR: 7.6; 95% IC: 1.9-30.9). Nevertheless, a trend to present more dental abnormalities (OR: 3.6; 95% IC: 0.9-13.4) was observed. Metatarsal stress fractures were also more frequent (4 vs 0; p < 0.05) in this group. Regarding laboratory features, median ALP levels were lower in subjects with ALPL variants (26 vs 29 IU/L; p < 0.005). Interestingly, the threshold of ALP levels < 25 IU/L showed a specificity, positive predictive value and positive likelihood ratio of 97.8, 94.4% and 19.8 to detect a positive ALPL test, respectively. CONCLUSIONS: In subjects with persistent hypophosphatasaemia -secondary causes excluded- one out of two presented ALPL variants. Musculoskeletal pain and ALP levels < 25 IU/L are associated with this variant(s). In this scenario, ALP levels < 25 IU/L seem to be very useful to identify individuals with the presence of an ALPL variant.