Magister Public Health - MPH / Background: The Provincial Government Western Cape (PGWC) Department of Health identified a lack of data on inpatient diagnoses and procedures in a form suitable to use for operational, strategic as well as financial health care planning. The only format in which diagnostic and procedure data was available was a paper based one encompassing individual patient notes in folders and discharge summaries. Making the data available in a coded format within an electronic database would facilitate storage, analysis and utilisation of that data for health service planning. Recognising the lack of availability of such coded data, this study was undertaken to evaluate different coding systems for their ability to code data in order to assist in deciding which coding systems best fit the need to facilitate easy and accurate recording of data on diagnoses and procedures from patient records. The identification of the most appropriate coding system for the context in which the PGWC Department of health functions should facilitate the easy recording, storage and retrieval of data that is accurate, reliable and useful for management decision making and would support optimal patient care. Aim: The aim of the study was to evaluate a selection of potentially suitable coding systems in order to determine which would be best able to code public sector district and regional hospital diagnostic and procedure data in the Western Cape Province. Method: A cross sectional analytical study design was used. Discharge diagnosis and procedure data were extracted from 342 patient folders from 3 district and 3 regional public hospitals in the Western Cape. This yielded 221 different diagnostic concepts and 126 different procedure concepts. The diagnostic concepts were further grouped into “all” diagnostic concepts recorded, diagnostic concepts recorded as “symptoms only” and diagnostic concepts recorded as “proper diagnoses”. The diagnostic coding systems evaluated were ICD-10 (International Classification of Diseases), ICPC-2 (International Classification of Primary Care 2nd edition) and ICD-10 Condensed Morbidity List. The procedure coding systems evaluated were CCSA-2001 (Current Procedure Terminology for South Africa) ICD-9-CM (International Classification of Diseases Clinical Modification 9th revision) and ICPC-2. The diagnoses and procedures were then coded in all of the coding systems being evaluated. Each diagnosis and procedure concept was matched with its representing concept in the coding system and scored according to the ability of the coding system to provide an “exact” match which was scored as (3) or a “partial” match scored as (2) or a “poor” match scored as (1) or “no” match scored as (0). Results: ICD-10 was better able to code diagnoses obtained from district and regional hospitals in the Western Cape compared to ICPC-2 and ICD-10 Condensed Morbidity list. For all recorded diagnostic concepts, ICD-10 was able to score 82% of the concepts as either an “exact” or a “partial” match compared to 79% in ICPC-2 and 30% in ICD-10-CL. ICD-10 consistently performed best across different stratification of diagnostic concepts namely concepts recorded as “proper diagnoses”, concepts recorded from regional hospitals only, concepts recorded from district hospitals only, concepts designated as “common diagnoses” and for concepts designated as “very common diagnoses”. In addition ICD-10 had zero diagnostic concepts for which “no match” could be found. CCSA -2001 proved to be the best coding system for coding procedures across all hospitals with an overall percentage of “exact” and “partial” matches of 83% compared to 65% for ICD-9-CM and 39% for ICPC-2 and also proved to be best across all strata. Conclusion: There were striking differences between the evaluated coding systems with regard to their ability to code diagnoses and procedures in the evaluated district and regional hospitals in the Western Cape Province. ICD-10 covers the scope of clinical diagnoses in more accurate and specific detail than ICPC-2 and ICD-10 CL. Though ICPC-2 is simpler and easier to use than ICD-10, it is not as detailed and specific as the latter but it proved ideal for symptoms rather than for specific diagnoses. ICD-10 Condensed Morbidity List was shown to be inadequate for coding diagnoses. However the difference between the two, although statistically significant were not very large and given the ease of use of ICPC-2, it could be recommended for use. As for procedures CCSA-2001 was assessed as being the most appropriate for coding procedures recorded in this setting compared to the other coding systems. ICPC-2 performed poorest for coding procedures across all evaluated settings and thus would be inappropriate to use. ICD-10 in most comparisons performed second best to ICPC-2 in terms of coding ability for diagnoses and could be considered for recommendation as a diagnostic coding tool.