A study published in 1997 found an inverse association between death from coronary heart disease and frequency of orgasm even given the risk that myocardial ischaemia and myocardial infarction can be triggered by sexual activity. Excerpt: "The association between frequency or orgasm and all cause mortality was also examined using the midpoint of each response category recoded as number of orgasms per year. The age adjusted odds ratio for an increase of 100 orgasms per year was 0.64 (0.44 to 0.95)". That is, a difference between any two subjects appeared when one subject ejaculated at around two or more times per week than the other. Assuming a broad range average of between 3-5 ejaculations per week for a healthy males, this would mean 5-7 ejaculations per week. This is consistent with an article on the benefits against prostate cancer However, the article notes that "The question of causation is complex... several explanations are possible".