Out-of-Hospital Use of Proton Pump Inhibitors and Hypomagnesemia at Hospital Admission: A Nested Case-Control Study

Background: Case series suggest that long-term use of proton pump inhibitors (PPIs) is associated with hypomagnesemia, but the current literature lacks systematically collected data. Our aim was to examine whether hypomagnesemia at the time of hospital admission is associated with out-of-hospital use of PPIs. Study Design: Nested case-control study matched for age and sex. Setting & Participants: Data were collected retrospectively from a tertiary acute-care facility. Eligible cases consisted of 402 adults with hypomagnesemia (serum magnesium < 1.4 mEq/L) at the time of hospital admission to medical services, age-and sex-matched with 402 control individuals with normal serum magnesium levels (1.4-2.0 mEq/L). Predictor: Out-of-hospital PPI use was identified in the hospital record. An omeprazole equivalent dose was calculated when possible. Covariates included the Charlson-Deyo comorbidity index, diabetes, diuretic use, estimated glomerular filtration rate, and gastroesophageal reflux. Outcome: Multivariable conditional logistic regression analyses were used to examine the association of PPI use with hypomagnesemia at the time of hospital admission. Results: PPI use was not associated with hypomagnesemia (adjusted OR, 0.82; 95% CI, 0.61-1.11). Neither PPI type nor omeprazole equivalent daily dose was associated with hypomagnesemia. Sensitivity analyses of PPI use restricted to patients with esophageal disorders (adjusted OR, 1.00; 95% CI, 0.69-1.45), severe hypomagnesemia (magnesium, <= 1.0 mEq/L; adjusted OR, 0.78; 95% CI, 0.13-4.61), or estimated glomerular filtration rate >= 60 mL/min/1.73 m(2) (adjusted OR, 0.84; 95% CI, 0.53-1.34) were unrevealing. Limitations: Exposure misclassification; hospitalized patients on medical services may not be representative of a broader ambulatory-based population. Conclusions: In a hospital-based adult population, out-of-hospital PPI use is not associated with hypomagnesemia at the time of hospital admission to medical services. In light of these inconclusive results, prospective cohort studies are needed to address this rare potential medication-related adverse effect. (C) 2013 by the National Kidney Foundation, Inc.