Association between serum alkaline phosphatase and bacteraemia in haemodialysis outpatients: a multicentre retrospective cross-sectional study

Abstract

ObjectivesElevated baseline serum alkaline phosphatase (ALP) may correlate with higher medium-term to long-term mortality in the general population and in patients with chronic kidney disease. However, few data are available on the association between serum ALP and the short-term prognosis of patients on haemodialysis (HD). We verified the association of ALP levels and bacteraemia or death in maintenance HD patients suspected of bacteraemia in an outpatient setting.DesignWe analysed 315 consecutive HD patients suspected of having bacteraemia with two sets of blood culture drawn on admission.SettingAdmission to two tertiary-care university medical centres from January 2013 to December 2015.ParticipantsConsecutive cases on maintenance HD aged≥18 years. Cases of hospitalised patients who had been transferred from another hospital, had a dialysis vintage<2 months, were also undergoing peritoneal dialysis, and/or were receiving HD less than once a week were excluded.Primary and secondary outcome measuresPrimary outcome measure was bacteraemia and secondary outcome was in-hospital death.ResultsAmong 315 cases included in the study, 187 had baseline-measured ALP levels, with a cut-off value on ROC analysis of 360 U/L (Area Under the Curve (AUC) 0.60, sensitivity 0.49, specificity 0.76). In multivariate analysis, there was a statistically significant association between a higher ALP in hospital visit and bacteraemia (OR: 2.37, 95% CI: 1.17 to 4.83). However, there were no statistically significant associations between higher ALP and in-hospital death (OR: 1.20, 95% CI: 0.57 to 2.54). A sensitivity analysis of 187 patients with no missing ALP values also demonstrated a significant association between elevated ALP and bacteraemia, but no significant association between ALP and in-hospital death.ConclusionsElevated ALP is a predictor of bacteraemia. In HD patients suspected of bacteraemia in outpatient settings, increased ALP levels were associated with increased likelihood of confirmed disease.