AN ASSESSMENT OF DATA QUALITY IN THE VERMONT-OXFORD TRIALS NETWORK DATABASE

The Vermont-Oxford Trials Network is a voluntary collaborative researc h group of neonatologists that maintains a database for very low birth weight infants (501-1500 g). The database (1)provides core data for ra ndomized trials, (2) serves as a resource for outcomes research in neo natology, and (3) generates quality management reports for participati ng sites. To assess the reliability of this database and to determine the sources of error, we reviewed 635 medical records chosen at random from among the 4341 eligible infants born at 40 participating data ge nerating sites during an 18-month period beginning January 1, 1990. Th e estimated frequencies of disagreement between the medical record and database for each of the 10 data items studied and the standard error s of the estimates (in parentheses) were: date of birth 1.3% (0.4), da te of admission 2.5% (0.6), date of discharge 8.8% (1.0), birthweight (difference > 50 g) 2.9% (0.6), location of birth (inborn or outborn) 2.1% (0.5), multiple birth 2.2% (0.5), cesarean section 2.5% (0.6), ge nder 2.1% (0.5), status 28 days after birth 3.4% (0.6), final status 2 .9% (0.6). The overall proportions and mean values for items in the da tabase were close to the estimated values based on the random sample o f records. There were a total of 247 disagreements between the databas e and the medical records in the sample. Twenty-three were due to data keying errors. Two hundred twenty-four were due to errors in transcri ption or interpretation. The rate of data keying errors decreased from over 50 errors per 10,000 fields to less than 15 errors per 10,000 fi elds when specific quality control procedures, including visual inspec tion, were instituted. Data keying errors accounted for 13.7% of all d isagreements between the database and medical record before improved d ata entry methods were introduced, and only 3.7% of all errors after t hey were introduced. We concluded that the Vermont-Oxford Trials Netwo rk Database is reliable. Data keying errors have been reduced by the i ntroduction of additional quality control measures. Further reductions in database errors will require measures aimed at minimizing transcri ption or interpretation errors by individuals completing the data form s.