24-HOUR PATTERN IN EMERGENCY DEPARTMENT PRESENTATION FOR SICKLE-CELL VASOOCCLUSIVE PAIN CRISIS

The objective of this study was to determine if a significant temporal pattern exists in the presentation of sickle cell vaso-occlusive pain crisis (SCVPC) 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 t o the ED of a university-affiliated hospital between January 1, 1991 a nd April 30, 1993. Data for adult subjects (greater than or equal to 1 5 years) were used for analysis. Date and time of presentation for eac h patient were recorded. Data were submitted to chi(2) and single cosi nor analysis for determination of circadian and circannual patterns. c hi(2) analysis suggested that the incidence of SCVPC events treated in the ED was not equally distributed throughout the 24 h. Single cosino r analysis identified a significant circadian rhythm (p < 0.001) for a ll 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 temp oral pattern in SCVPC presentation to the ED may lead to identificatio n and control of conditions that precede the occurrence of a SCVPC. In terventions for SCVPC may require modification based on chronobiologic al trends.