Chronobiological rhythms in onset of massive pulmonary embolism in Iranian population.

BACKGROUND To investigate whether there is any chronobiological rhythms in onset of massive pulmonary embolism in Iranian population and to study any time variation in occurrence of this disease in patients' subgroups. METHODS This study was conducted in an emergency department of a referral teaching hospital from March 2003 to March 2007. All medical records of patients with definite diagnosis of massive pulmonary embolism were reviewed for chronobiological rhythms in hourly, daily, monthly and season periods. RESULTS One hundred and twenty patients (49 women and 71 men) included in the study. The mean age of patients was 63.63 +/- 17.21 years. Massive pulmonary embolism showed a statistical increase in onset in the morning period (p = 0.004) with peak of occurrence between 9:00 to 10:00, in the first three day of the week (p < 0.001), and during winter (p = 0.003). In addition, hourly and weekly rhythms in onset of massive pulmonary embolism in diabetic patients is different from nondiabetic patients and occur most frequent in evening hours and in the end of week. CONCLUSION Our findings revealed that massive pulmonary embolism has a peak of onset during morning hours and in the winter. We also found that massive pulmonary embolism also has a weekly rhythm. Circadian and weekly rhythms of massive pulmonary embolism were different in diabetic patients and this is a novel finding of this study.