Cut-offs and response criteria for the Hospital Universitario la Princesa Index (HUPI) and their comparison to widely-used indices of disease activity in rheumatoid arthritis

Objective To estimate cut-off points and to establish response criteria for the Hospital Universitario La Princesa Index (HUPI) in patients with chronic polyarthritis. Methods Two cohorts, one of early arthritis (Princesa Early Arthritis Register Longitudinal PEARL] study) and other of long-term rheumatoid arthritis (Estudio de la Morbilidad y Expresión Clínica de la Artritis Reumatoide EMECAR]) including altogether 1200 patients were used to determine cut-off values for remission, and for low, moderate and high activity through receiver operating curve (ROC) analysis. The areas under ROC (AUC) were compared to those of validated indexes (SDAI, CDAI, DAS28). ROC analysis was also applied to establish minimal and relevant clinical improvement for HUPI. Results The best cut-off points for HUPI are 2, 5 and 9, classifying RA activity as remission if =2, low disease activity if >2 and =5), moderate if >5 and <9 and high if =9. HUPI''s AUC to discriminate between low-moderate activity was 0.909 and between moderate-high activity 0.887. DAS28''s AUCs were 0.887 and 0.846, respectively; both indices had higher accuracy than SDAI (AUCs: 0.832 and 0.756) and CDAI (AUCs: 0.789 and 0.728). HUPI discriminates remission better than DAS28-ESR in early arthritis, but similarly to SDAI. The HUPI cut-off for minimal clinical improvement was established at 2 and for relevant clinical improvement at 4. Response criteria were established based on these cut-off values. Conclusions The cut-offs proposed for HUPI perform adequately in patients with either early or long term arthritis

Influence of polymer composition on the sensitivity towards nitrite and nitric oxide of colorimetric disposable test strips

The influence of polymer composition on the sensitivity towards nitrite (NO 2 − ) and nitric oxide (NO) of a series of 19 polymeric hydrogel films has been stud- ied. The polymers, based on the hydrophilic monomer 2- hydroxyethylmethacrylate (HEMA), are able to encapsu- late the colorimetric indicator 1,2-diaminoanthraquinone (DAQ) and to respond to NO 2 − and NO by visual chang- es. In the case of nitrite, the calculated limits of detection (LOD) for two of the polymeric sensors (10 μ M) are very close to the sensitivity estimated for free DAQ in solution (LOD 5 μ M), but with the advantage of a solid supported sensor with the format of a disposable test- strip made with affordable starting chemicals. The re- sults are interpreted taking into account the nature and proportions of monomers and cross-linkers used for the synthesis of polymers. Key factors for obtaining sensi- tive materials are the hydro philic character of the film along with the utilization of low levels of cross-linker and the use of an acidic monomer, like acrylic acid, as a building block.Financial support from the Spanish MINECO (CTQ2015-68429-R) and Fundació Caixa Castelló-UJI (P1·1B2015-76) is acknowledged. V. F. thanks the financial support from UJI (predoctoral fellowship). We thank SCIC/UJI for technical assistance