Validity and reliability of the minimum basic data set in estimating nosocomial acute gastroenteritis caused by rotavirus.

INTRODUCTION Rotavirus is the principal cause of nosocomial acute gastroenteritis (NAGE) under 5 years of age. The objectiveis to evaluate the validity and reliability of the minimum basic dataset (MBDS) in estimating the NAGE caused by rotavirus (NAGER) and to analyze any changes during the three years that the Rotarix® and Rotateq® vaccines were used in Spain. MATERIAL AND METHODS A descriptive, retrospectivestudy was carried out in the University Hospital of Guadalajara(UHG) (Spain) between 2003-2009 using the MBDS, positive microbiological results for rotavirus (PMRs), and medical histories.Three methods of estimation were used: 1) An ICD-9-CM code 008.61 in the secondary diagnosis fields (DIAG2) of MBDS; 2) method 1 and/or PMRs with a current or recent hospitalization; and 3) the reference method or method 2 contrasted with patient medical histories. The validity of methods 1 and 2 was determined -sensitivity, specificity, predictive values and likelihood ratios (LRs)-, along with their agreement with method 3 (Kappa coefficient). In addition, the incidence rate ratio between the NAGER rate in 2007-2009 (commercialization period of both vaccines) was calculated with respect to 2003-2005 (precommercialization period). RESULTS Method 1 identified 65 records with a DIAG2 of 008.61. Method 2 found 62 probable cases, and the reference method, 49 true cases. The sensitivity of the MBDS was 67 %,the positive predictive value was 51 %, and both negative LR (LR-) and reliability were moderate (LR- 0.33, Kappa coefficient 0.58). During 2007-2009, the NARGE decreased by 5 cases per 103 hospitalizations and by 9 per 104 days of hospitalization. Method 2 overestimated both the decline in incidence by 2 per 103 hospitalizations and the decreased risk per day of stay by 10 %. The MBDS found no differences between the two three-year periods, but, like method 2, showed an excellent level of diagnostic evidence (LR+ 67). CONCLUSION The MBDS taken together with microbiological results, is more exact, safer and more reliable than the MBDS alone in estimating NAGER; and more useful in ruling out it. Nevertheless, the MBDS alone may be used to estimate and compare such disease in contexts with different prevalences.