Discordance between two national health statistics sources (EMH and EESCRI, 1990–2009). Analysis of psychiatric morbidity

Abstract Introduction Two statistical sources provide data on hospital stays and discharges for all Spanish hospitals: Hospital Morbidity Survey (acronym in Spanish: EMH) and Statistics of Health Establishments providing Inpatient Care (acronym in Spanish: EESCRI). Our aim is to contrast these two statistical sources to define their accuracy and relevance in psychiatric epidemiology studies. Material and methodology The analysis is based on two aspects: (1) Compare the number of psychiatric stays and hospital discharges from 1990 to 2009. (2) Analyse and compare how the average stay is provided. Results The differences between the two statistical sources are significant and increase over time. In 2005–2009 the EMH records 121% of hospitalisations (577,078 vs 475,414) and 46% (14,239,527 vs 30,821,412) of psychiatric stays, compared with EESCRI. Moreover, the average stay estimated by EESCRI shows serious methodological problems, particularly in settings of prolonged hospitalisation (psychiatric hospitals); the estimations are potentially below the real value. Conclusions Surprisingly, the questionnaires completed by hospitals to develop the EESCRI provide data on assisted morbidity quite different from that provided by the EMH, despite both statistical sources having the same inpatient records for data processing. It is difficult to attribute these differences to sampling error, as the EMH has a very high sampling fraction, which minimises the sampling error. Given the mismatch between sources, we recommend using the EMH, as it offers more reliable data and allows an accurate determination of the length of stays.