Objective Prolonged QT interval predisposes to ventricular arrhythmias and sudden cardiac death. However, the association between QT interval and mortality by the level of pre-existing kidney function has not been investigated.
Methods We followed 6565 participants from the National Health and Nutrition Examination Survey III for a median of 13.3 years. Sample divided according to corrected QT (QTc) interval was as follows: normal (QTc <450 ms for men and <460 ms for women) or prolonged. It was further categorised as follows: (1) no chronic kidney disease (CKD), that is, albumin to creatinine ratio (ACR) <30 mg/g and estimated glomerular filtration rate (eGFR) > 60 mL/min/1.73 m2 ⇓; (2) CKD by eGFR only (eGFR <60 mL/min/1.73 m2, ACR <30 mg/g); (3)⇓ CKD by ACR only (ACR >30 mg/g, eGFR >60 mL/min/1.73 m2) and ⇓(4) CKD by both. Cox proportional hazards models were used.
Results CKD group had prolonged QTc than those without CKD (20.5%vs12.9%, p<0.0001). Both prolonged QTc and CKD are independently associated with increased risk of mortality. When combined, risk of mortality is higher in those with CKD by eGFR with prolonged QTc than normal QTc (HR 2.6 (1.7–3.9) and 3.1 (1.7–5.4) vs 1.4 (1.1–1.7) and 1.7 (1.3–2.1) for all-cause and CV mortality). There is no significant difference in risk in those with CKD by ACR when QTc is prolonged. There is significant improvement in risk prediction for all-cause and CV mortality when QTc is added to CKD beyond established CV risk factors (net reclassification index p<0.00001).
Conclusion A screening ECG in those with CKD may help in finer risk stratification and may be considered.
- renal disease
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Contributors RM, SW and SEW did substantial contributions to the conception and design of the work.RM, SW and SEW work with the acquisition, analysis and interpretation of data for the work. DP and JP drafted the work and revised it critically for important intellectual content. RM, SW, SEW, JP and DP were involved in the final approval of the version to be published. RM and SW worked in agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Competing interests None declared.
Ethics approval We used data from the National Health and Nutrition Examination Survey (NHANES). The National Center for Health Statistics of the Centers for Disease Control and Prevention institutional review board approved the protocol for NHANES. All participants gave written informed consent.
Provenance and peer review Not commissioned; internally peer reviewed.
Data sharing statement There are no additional data available for this paper.
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