“…Clearly, there is confusion in differentiating between a comorbidity, secondary diagnosis and complication when defining comorbidity (Greenfield et al 1988, Jencks et al 1988, Iezzoni et al 1992. Some authors state that the comorbidity has to be a medical problem (Munoz et al 1988, Katz et al 1996, Thomas 1997, not related to the primary diagnosis (Iezzoni et al 1992), chronic (Manton et al 1991, Iezzoni et al 1992, Librero et al 1999, Fillenbaum et al 2000, or inclusive of acute diseases (Feinstein 1970, Greenfield et al 1988, Thomas 1997, or a combination of acute and chronic diseases (Jones et al 1999, Librero et al 1999. Such ÔnondiseaseÕ entities' as pregnancy (Feinstein 1970), or curable states of health such as tinea and dental problems (Liu et al 1999), nosocomial infections and pressure sores (Greenfield et al 1988) have been considered to be comorbidities, whilst cancer has been excluded (Romano et al 1993).…”