Condition-related factors represent particular illness-related demands faced by the patient. Some strong
determinants of adherence are those related to the severity of symptoms, level of disability (physical,
psychological, social and vocational), rate of progression and severity of the disease, and the availability
of effective treatments.Their impact depends on how they influence patients’ risk perception, the
importance of following treatment, and the priority placed on adherence. Co-morbidities, such as
depression (18) (in diabetes or HIV/AIDS), and drug and alcohol abuse, are important modifiers of adherence
behaviour.