Obesity and sickness absence: results from the CHAP study.

BACKGROUND: Obesity is an increasing public health problem. A small number of studies have examined the relationship between obesity and sickness absence, with mixed results, particularly regarding short-term sickness absence. AIMS: To determine if obesity is associated with short- and long-term sickness absence and to investigate the mechanisms that may underlie any association.
METHODS: Cross-sectional (n = 1489) and prospective (n = 625) analyses were conducted on staff from London Underground Ltd. All participants underwent regular clinical examinations that involved their height and weight being measured, obesity-related medical problems being diagnosed and psychiatric disorders being identified. The number of days taken for short- (<10 days in an episode) and long-term sickness absence were recorded by managers on an electronic database.
RESULTS: There was a positive linear association between employees' body mass index (BMI) and the number of days' work missed due to sickness absence on both cross-sectional and prospective analyses (P < 0.001). Obesity was a risk factor for both short- and long-term sickness absence. Obese individuals typically took an extra 4 days sick leave every year. The majority of the increased risk for long-term sickness absence appeared to be mediated via co-morbid chronic medical conditions. The excess short-term sickness absence was not explained by obesity-related medical problems, psychiatric disorders or workplace factors.
CONCLUSIONS: Obese employees take significantly more short- and long-term sickness absence than workers of a healthy weight. There is growing evidence to support employers becoming more involved in tackling obesity.