However, while many in this group suffered from long working hours, ever-increasing responsibility at work, frequent business travel, irregular work schedules and shift-work, other factors such as smoking, drinking, obesity, and family medical histories may all have contributed to their medical problems. Thus they realized that it is the interaction between all of these factors that is critical, rather than any one single cause.
只是，雖然這些案例都有超時工作、工作負荷增加、經常出差、不規律工作和輪班等現象，但由於個人也有傳統心血管疾病的危險因子，如抽菸、喝酒、肥胖、家族病史等，只能得到工作與疾病會「交互作用」的初步結論。