RT Journal Article
SR Electronic
T1 Persistently normal blood tests in patients taking methotrexate for RA or azathioprine for IBD: a retrospective cohort study
JF British Journal of General Practice
JO Br J Gen Pract
FD British Journal of General Practice
SP BJGP.2021.0595
DO 10.3399/BJGP.2021.0595
A1 Simon DS Fraser
A1 Sharon X Lin
A1 Matthew Stammers
A1 David Culliford
A1 Kinda Ibrahim
A1 Ravina Barrett
A1 Clare Howard
A1 Ruth Johnson
A1 Nicola Barnes
A1 James Batchelor
A1 Christopher Holroyd
A1 Jo Adams
A1 Adam Rischin
A1 Paul Roderick
A1 Paul Rutter
A1 Christopher J Edwards
YR 2022
UL http://bjgp.org/content/early/2022/03/09/BJGP.2021.0595.abstract
AB Background Disease-modifying anti-rheumatic drugs (DMARDs), including methotrexate and azathioprine, are commonly used to treat rheumatoid arthritis (RA) and inflammatory bowel disease (IBD). Blood-test safety monitoring is mainly undertaken in primary care. Normal blood results are common.Aim To determine the frequency and associations of persistently normal blood tests in patients with RA prescribed methotrexate, and patients with IBD prescribed azathioprine.Design and setting Two-year retrospective study of a cohort taken from an electronic pseudonymised primary care/laboratory database covering >1.4 million patients across Hampshire, UK.Method Patients with RA and IBD, and associated methotrexate and azathioprine prescriptions, respectively, were identified. Tests and test thresholds recommended by the National Institute for Health and Care Excellence were applied. Persistent normality was defined as no abnormalities of any tests nor alanine aminotransferase (ALT), white blood count (WBC), neutrophils, and estimated glomerular filtration rate (eGFR) individually. Logistic regression was used to identify associations with test normality.Results Of 702 265 adults, 7102 had RA and 8597 had IBD. In total, 3001 (42.3%) patients with RA were prescribed methotrexate and 1162 (13.5%) patients with IBD were prescribed azathioprine; persistently normal tests occurred in 1585 (52.8%) and 657 (56.5%) of the populations, respectively. In patients with RA on methotrexate, 585 (19.5%) had eGFR, 219 (7.3%) ALT, 217 (7.2%) WBC, and 202 (6.7%) neutrophil abnormalities. In patients with IBD on azathioprine, 138 (11.9%) had WBC, 88 (7.6%) eGFR, 72 (6.2%) ALT, and 65 (5.6%) neutrophil abnormalities. Those least likely to have persistent test normality were older and/or had comorbidities.Conclusion Persistent test normality is common when monitoring these DMARDs, with few hepatic or haematological abnormalities. More stratified monitoring approaches should be explored.