Darby Martin, Jeet Thaker, Maria Shreve, Lois Lamerato, Kartazyna Budzynska
Journal: BMJ nutrition, prevention & health 2021;4(1):30-35
PMID: 34308109
Vitamin B12 is a water-soluble vitamin. Medications including proton pump inhibitors, histamine H2 blockers and metformin have also been shown to cause vitamin B12 deficiency. The aim of this study was to investigate the use of vitamin B12 testing in a large cohort of patients on metformin and assess the benefit to formulating screening recommendations for vitamin B12 deficiency. This study is a retrospective cohort study of 13489 patients who were exposed to metformin. Results show that patients who are greater than 65 years old and patients who have been taking metformin for more than 5 years are at increased risk of vitamin B12 deficiency. Furthermore, the African-American population was tested at a lower rate (41.62%) compared with the non-African-American population (44.9%), showing a 15% less likelihood of being tested compared with the other ethnic groups. Authors conclude that physicians should be aware of the increased incidence of vitamin B12 deficiency in particular population cohorts.
OBJECTIVES
Our study investigated the use of vitamin B testing in a large cohort of patients on metformin and assesses appropriateness and benefits of screening recommendations for vitamin B deficiency.
DESIGN
This retrospective cohort study included insured adult patients who had more than 1 year of metformin use between 1 January 2010 and 1 October 2016 and who filled at least two consecutive prescriptions of metformin to establish compliance. The comparison group was not exposed to metformin. Primary outcome was incidence of B deficiency diagnosed in patients on metformin. Secondary outcome was occurrence of B testing in the patient population on metformin. Records dated through 31 December 2018 were analysed.
SETTING
Large hospital system consisting of inpatient and outpatient data base.
PARTICIPANTS
A diverse, adult, insured population of patients who had more than 1 year of metformin use between 1 January 2010 and 1 October 2016 and who filled at least two consecutive prescriptions of metformin.
RESULTS
Of 13 489 patients on metformin, 6051 (44.9%) were tested for vitamin B deficiency, of which 202 (3.3%) tested positive (vs 2.2% of comparisons). Average time to test was 990 days. Average time to test positive for deficiency was 1926 days. Factors associated with testing were linked to sex (female, 47.8%), older age (62.79% in patients over 80 years old), race (48.98% white) and causes of malabsorption (7.11%). Multivariable logistic regression showed older age as the only factor associated with vitamin B deficiency, whereas African-American ethnicity approached significance as a protective factor.
CONCLUSIONS
Based on our study's findings of vitamin B deficiency in patients on metformin who are greater than 65 years old and have been using it for over 5 years, we recommend that physicians consider screening in these populations.
© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.
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