Heat illness symptom index (HISI): a novel instrument for the assessment of heat illness in athletes.
BACKGROUND
Heatstroke is the third leading cause of death in athletics, and an important cause of morbidity and mortality in exercising athletes. There is no current method, however, for identifying milder forms of heat illness. In this pilot study, we sought to develop and provide initial validation for a Heat Illness Symptom Index scale (HISI) that would facilitate research in the assessment of milder forms of heat illness in athletes.


METHODS
The study was designed as a multimodal prospective observational study of Division I football players during twice daily practices in southern Florida. We developed a 13-item scale that assessed symptoms that are suspected to occur during milder forms of heat illness. The resultant scale was assessed for reliability using Cronbach's alpha, and was assessed for construct validity by correlating scale scores with factors that are known to be related to heat illness. HISI scores, as well as data on perceived exertion, player position, and pre and post practice weights were collected from 95 athletes participating in late summer football practices. A total of 557 athlete sessions were analyzed.


RESULTS
The mean score on the heat illness symptom scale was 12.1 (SD 13.8) and the median value was 8.0. Cronbach's alpha confirmed suitable internal consistency of the scale when assessed separately for each of the five morning practices (alpha = 0.91, 0.88, 0.82, 0.92, 0.85). There were statistically significant correlations of the scale score with weight loss during practice (P = 0.006), rating of perceived exertion (P = 0.005), player position (P < 0.0001), and ambient heat index (P = 0.02) as hypothesized.


CONCLUSIONS
This pilot study provides initial validation for a novel symptom-based tool for use in assessing mild forms of heat illness in an athletic population. Further validation studies of the instrument, and correlating symptom scores with measures of core temperature, are needed and planned.
Coris
Eric E
EE
University of South Florida College of Medicine, Department of Family Medicine, Division of Sports Medicine, Tampa, FL 33612, USA. ecoris@hsc.usf.edu
Walz
Stephen M
SM
Duncanson
Robert
R
Ramirez
Arnold M
AM
Roetzheim
Richard G
RG
D001835:Body Weight / Q000502:physiology; D003681:Dehydration / Q000503:physiopathology; D005538:Football / Q000502:physiology*; D006305:Health Status Indicators; D018883:Heat Stroke / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D015999:Multivariate Analysis; D005082:Physical Exertion / Q000502:physiology; D010865:Pilot Projects; D011446:Prospective Studies; D015203:Reproducibility of Results; D012307:Risk Factors; D012720:Severity of Illness Index; D013178:Sports Medicine / Q000379:methods*