Cost of medication errors in rheumatic patients in Mexico.

This study aims to measure the frequency of medication error (ME) in rheumatology outpatients of the Social Security System (SS) in Mexico and to measure the costs by comparing the days lost at work as direct consequence of the medication error against the theoretical cost of no error in the process. A prospective 6-month survey was conducted in a reference hospital in Guadalajara, Mexico. ME was defined as any discrepancy between the prescription and medicine taken by patients. The origin of the discrepancy was identified and registered. We present 381 patients: 292 with rheumatoid arthritis, 57 with ankylosing spondylitis, and 32 with systemic lupus erythematosus. One hundred twenty seven (33%) had medication errors. Ninety eight (77%) got worse in their condition due to ME. Forty percent of MEs were due to patients' decisions, 41% to a lack of availability of medication which should have been provided by SS, and 18% to a non-justified medical decision by primary-care providers. Patients lost in average 3 working days each month because of the ME. The cost of ME is high. In the case analyzed, opportune access to treatment represents a lower cost for the system, but it represents a significant loss of days at work each month. ME is a signal of a system failure. Inter-professional teamwork is needed to perfect the system.