Key result
Older adults (>=60 years) had longer QTc intervals than younger adults (433.7 vs 427.4 ms; p=0.008), and females had longer QTc than males in both age groups (by 14.6 and 11.6 ms; both p<0.001).
Why the study?
ECG reference values used in Nigerian diagnostic centres are derived from European and North American cohorts, while age- and sex-stratified Nigerian data are scarce.
Cross-Sectional (n=313)
Unblinded cardiac physiologist re-measurement
No
In a Nigerian diagnostic centre cohort with normal ECGs, females consistently had longer QTc intervals than males across age groups and older adults had modestly longer QTc intervals, though pre-selection by conventional normality limits likely masked age-related conduction differences in PR and QRS intervals.
Answers are grounded in this paper and cite their sources.
Extends QTc age and sex differences to Nigerian adults with normal ECGs; confirms prior patterns but leaves local thresholds open pending prospective data.
BACKGROUND: Electrocardiographic (ECG) reference values used in Nigerian diagnostic centres are derived from European and North American cohorts, and age- and sex-stratified Nigerian data are scarce. METHODS: In this retrospective cross-sectional study, 313 12-lead ECGs reported as normal by a cardiologist at a diagnostic centre in Owerri, Nigeria, were grouped by age (18-40 years, n = 164; ≥ 60 years, n = 149) and sex. Heart rate, P-wave duration, PR interval, QRS duration and machine-reported QTc were compared using t-tests or Mann-Whitney U tests and two-way ANOVA, with Bonferroni correction. Sensitivity analyses applied conventional limits uniformly. RESULTS: Heart rate, P-wave duration, PR interval and QRS duration did not differ between age groups (all p > 0.09). QTc was longer in older adults (433.7 ± 17.4 vs. 427.4 ± 18.3 ms; p = 0.008), also after heart-rate adjustment (8.3 ms; 95% CI 4.8 to 11.8). Females had longer QTc than males in both age groups (by 14.6 and 11.6 ms; both p < 0.001) in all analyses. Males had wider QRS than females only in younger adults (95.7 vs. 89.5 ms; p < 0.001), but this age-by-sex interaction (p = 0.007) was not significant when limits were applied uniformly (p = 0.076). PR stopped at 200 ms in both age groups, consistent with selection. CONCLUSION: The female-longer QTc was the most consistent finding, and older adults had modestly longer QTc. Age-related conduction differences may have been masked by selection; unselected multicentre data are needed before reference intervals are adopted.
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Egharevba et al. (2026) conducted a cross-sectional in Normal 12-lead ECGs in adults (n=313). Older age (>=60 years) and sex differences vs. Younger age (18-40 years) and opposite sex was evaluated on Machine-reported QTc interval (ms) between older (>=60 years) and younger (18-40 years) adults (MD 6.3 ms (Younger minus Older 95% CI -10.26 to -2.33; Cohen's d -0.35; heart-rate and sex-adjusted MD 8.3 ms, 95% CI 4.8 to 11.8), 95% CI -10.26 to -2.33, p=0.008). Older adults (>=60 years) had longer QTc intervals than younger adults (433.7 vs 427.4 ms; p=0.008), and females had longer QTc than males in both age groups (by 14.6 and 11.6 ms; both p<0.001).
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