Twenty-four-hour pattern in emergency department presentation for sickle cell vaso-occlusive pain crisis.

The objective of this study was to determine in a significant temporal pattern exists in the presentation of sickle cell vaso-occlusive pain crisis (SC-VPC) patients to an emergency department (ED) for treatment. This 28-month retrospective study of ED sickle cell crisis treatment involved 1128 presumably diurnally active SCVPC patients presenting to the ED of a university-affiliated hospital between January 1, 1991 and April 30, 1993. Data for adult subjects (> or equal to 15 years) were used for analysis. Date and time of presentation for each patient were recorded. Data were submitted to chi 2 and single cosinor analysis for determination of circadian and circannual patterns. chi 2 analysis suggested that the incidence of SCVPC events treated in the ED was not equally distributed throughout the 24 h. Single cosinor analysis identified a significant circadian rhythm (p < 0.001) for all subjects, with peak ED presentations occurring in the early evening. The best-fit cosine curve accounted for 50% of the sample variance. While the etiology of this finding is unclear, determination of a temporal pattern in SCVPC presentation to the ED may lead to identification and control of conditions that precede the occurrence of a SCVPC. Interventions for SCVPC may require modification based on chronobiological trends.