Introduction: Because of importance of coded data in quality management activities, case-mix management, planning, marketing, research activities, fee-for-services initiatives, patient safety monitoring, the development of clinical decision support tools, and public health surveillance, observance of coding quality elements is necessary more than ever. Having thorough knowledge of the classification systems key component of data quality include validity, completeness, and timeliness are necessary. In this study, validity, completeness, and timeliness of coding were compared among medical universities located in Tehran namely Iran, Tehran, and Shaheed Beheshti.

Methods: This descriptive-comparative study conducted between 22Marh and 22 Oct. 2007). Research population was included medical records of discharged inpatients of all medical universities located in Tehran, namely Iran (10 hospitals), Tehran (9 hospitals) and Shaheed Beheshti (10 hospitals) respectively. Data collection was done through direct observation by using 1 checklist to determine observance rate of validity, completeness, and timeliness. Data analysis was done using descriptive statistics and SPSS software.

Results: Observance rate of validity of coding, in Iran, Tehran and Shaheed Beheshti Medical Sciences Universities for main diagnosis were 83.3%, 79.23%, and 85.53% respectively and 79.46%, 75.04%, 88.87% for other diagnosis. For main procedures 85.23%, 80.62%, and 85.41% and 80.84%, 84.49%, 91.3% for other procedure. Observance rate of coding completeness, in above Universities for main diagnosis were 93.06%, 96.91%, 97.96% respectively, and for other diagnosis 88.08%, 90.76%, 95.02%, and 96.7%, 94%, 98.93% for main procedure, and 93.85%, 97.35%, 95.65% for other procedure. Only 20 percent (2 hospitals) of 33 hospitals were observed for timeliness of coding.

Conclusion: Although, observance rate of completeness of coding to some extent have improved against to past, but not validity rate of coding and still combined with some problems. Also majority of hospitals had excessive difference with World Health Organization standards for timeliness of coding. Thus, critical activities are necessary for improving coding quality in these areas.