Summary of evidence
This study investigated if there is a significant association between the presence of a diagonal ear lobe crease (DELC) and coronary artery disease (CAD) independent of age. By using the gold standard diagnosis for CAD, angiography, we were able to provide a more objective analysis than other reviews which have included autopsy studies and clinically diagnosed heart disease(3). Our study found that patients with DELC have an increased likelihood of having CAD. Also despite some previous studies suggesting that DELC was simply a result of age, all ten of the included studies that looked at this found that the relationship between DELC and CAD was independent of age and all other conventional cardiovascular risk factors.
We also looked to see if the diagnostic odds ratio varied between different cohorts. In looking at different age groups, only one study(6) provided their findings for each age bracket and although it found that the diagnostic odds ratio was greatest in the youngest cohort, the population size of each cohort was relatively small and it is difficult to assess the validity of this finding without other studies. Similarly, only one study looked at different odds ratio between genders and found that it was greater in women than men (OR 6.368 vs 5.420) however it is difficult to assess this effect overall in our analysis as there was frequently a disparate gender ratio between the case and control groups. Whilst this is due to poor recruitment, it may partly be influenced by there being a reduced prevalence of CAD in women and also some studies excluding patients with ear lobe piercings causing an iatrogenic DELC. Other studies(20) have found no difference in the prevalence of DELC between males and females.
As the included studies spanned eight different countries it is believed that the results are applicable to multiple ethnic populations. However it is difficult to determine the impact of ethnicity especially as there are few studies which look at the general prevalence of DELC in a healthy population. Without knowing the generalised prevalence of DELC and relationship with CAD in different populations it is difficult to ascertain the impact of ethnicity.
Although this study found that patients with DELC have an increased likelihood of having CAD, there was wide variance in the sensitivity and specificity of DELC as a diagnostic test. This supports findings from other studies that indicate DELC should only be used as a physical marker not a diagnostic clinical test for CAD(12).