Study designs of evaluations included in the review
Observational studies were eligible for inclusion. Diagnostic case-control studies comparing patients with known LVH with healthy controls were excluded.
Specific interventions included in the review
Studies evaluating the accuracy of ECG indices for the diagnosis of LVH were eligible for inclusion. The review focused on the six most commonly used indices: the Sokolow-Lyon index, Cornell voltage index, Cornell product index, Gubner index, and Romhilt-Estes using a score of 4 or more points and 5 or more points as the diagnostic threshold. Details of each of the indices were provided in the original paper.
Reference standard test against which the new test was compared
Studies using echocardiography as the reference standard were eligible for inclusion, provided left ventricular mass was indexed for body surface area and not heart mass/body height.
Participants included in the review
Studies of asymptomatic patients with primary arterial hypertension in any health care setting were eligible for inclusion. Studies were excluded if the patients had concomitant left anterior fascicular block, left bundle branch block, or had known left ventricular hypertrophy. The included studies assessed men and women from primary and secondary care settings. The median prevalence of LVH was 33% (interquartile range: 23, 41) in primary care settings and 65% (interquartile range: 37, 81) in secondary care settings.
Outcomes assessed in the review
Studies reporting sufficient data to construct a 2x2 contingency table for the calculation of sensitivity and specificity were eligible for inclusion. The main interest was in the negative likelihood ratio (LR) as ECG would mainly be used to rule out the diagnosis of LVH.
How were decisions on the relevance of primary studies made?
Two reviewers independently assessed studies for relevance against the inclusion criteria.