Time Out of Play Due to Illness in Major and Minor League Baseball

OBJECTIVE: To generate a summative report on the most commonly diagnosed illnesses in Major League Baseball (MLB) and Minor League Baseball (MiLB) athletes with specific attention to their impact based on time out of play. DESIGN: Retrospective analysis. SETTING: Injury and illness data from the MLB Health and Injury Tracking System. PARTICIPANTS: All MLB and MiLB athletes active between 2011 and 2016. ASSESSMENT OF RISK FACTORS: Illnesses were defined as atraumatic medical diagnoses that occurred during the MLB or MiLB season and resulted in at least 1 day out of play. MAIN OUTCOME MEASURES: Incidence of illness diagnoses and resulting time out play. RESULTS: Eight thousand eight hundred thirty-four illnesses were reported, representing 14.7% of all diagnoses resulting in time out of play. Total days missed (DM) due to illness were 39 614, with a mean of 4.6 (SD 9.9 days) and median 2 DM per diagnosis. The annual incidence of illness per season was 20.3 per 100 athletes. The most common diagnosis was nonspecific viral illness (15.3%), followed by gastroenteritis (13.6%), other gastrointestinal illness (8.3%), influenza (7.0%), and upper respiratory infection (6.2%). Appendicitis (15.2%) and Epstein-Barr virus/cytomegalovirus (9.1%) were the most common season-ending diagnoses. CONCLUSIONS: Illnesses represent a significant cause of time out of play in MLB and MiLB. Prevention efforts should focus on limiting the spread of communicable viral, respiratory, and gastrointestinal disease among players, as the majority of diagnoses fell into these categories. This work may be used to guide future research into illness treatment and prevention in professional baseball.