Purpose of the study Hypophosphataemia and hyperphosphataemia are frequently encountered in hospitalised patients and are associated with significant clinical consequences. However, the prognostic value of normal-range phosphorus levels on all-cause mortality and hospitalisations is not well established. Therefore, we examined the association between normal-range phosphorus levels, all-cause mortality and hospitalisations in patients presenting to the emergency department of a tertiary medical centre in Israel.
Study design A retrospective analysis of patients presenting to the Chaim Sheba Medical Center emergency department between 2012 and 2018. The cohort was divided into quartiles based on emergency department phosphorus levels: ‘very-low-normal’ (p ≥ 2 mg/dL and p ≤ 2.49 mg/dL), ‘low-normal’ (p ≥ 2.5 mg/dL and p ≤ 2.99 mg/dL), ‘high-normal’ (p≥ 3 mg/dL and p≤3.49 mg/dL) and ‘very-high-normal’ (p ≥ 3.5 mg/dL and p ≤ 4 mg/dL). We analysed the association between emergency department phosphorus levels, hospitalisation rate and 30-day and 90-day all-cause mortality.
Results Our final analysis included 223 854 patients with normal-range phosphorus levels. Patients with ‘very-low-normal’ phosphorus levels had the highest mortality rate. Compared with patients with ‘high-normal’ phosphorus levels, patients with ‘very-low-normal’ levels had increased 30-day all-cause mortality (OR 1.3, 95% CI 1.1 to 1.4, p<0.001), and increased 90-day all-cause mortality (OR 1.2, 95% CI 1.1 to 1.3, p<0.001). Lower serum phosphorus levels were also associated with a higher hospitalisation rate, both for the internal medicine and general surgery wards (p<0.001).
Conclusions Lower phosphorus levels, within the normal range, are associated with higher 30-day and 90-day all-cause mortality and hospitalisation rate.
- adult intensive & critical care
- diabetes & endocrinology
- general medicine (see internal medicine)
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Contributors All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by YB, EK, SS, EZ and EG. The first draft of the manuscript was written by GS and AL and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests All authors of the manuscript 'Normal-Range Serum Phosphorus levels are Associated with All-Cause Mortality: Should We Redefine our Reference Range?' have taken care to ensure the integrity of their work and their scientific reputation.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data may be obtained from a third party and are not publicly available. Data include deidentified participant data, which can be available upon request from firstname.lastname@example.org.
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