Influence of the 'directions for use' on positivity rates of the Hemoccult II test.

OBJECTIVE: A concise, detailed, and complete instruction sheet is indispensable for adequate completion by the users of a product. This sheet should be enclosed in the envelope which contains Hemoccult II slides. The authors found that the instructions provided by the French manufacturer were unsatisfactory. They designed a short and simple notice, adequately detailed to be understandable by all volunteers and to obtain satisfactory stool smears. Positivity rates of Hemoccult II performed with the manufacturer's notice were compared to those obtained with Hemoccult II performed with the authors' instructions. METHODS: This study was made during the third screening campaign carried out by the Office Departemental de Lutte contre le Cancer (ODLC). This screening programme only concerned women 59 to 69 years of age. Six thousand three hundred and ninety-two Hemoccult II containing the manufacturer's instructions were received at the laboratory during March, April, May, June and July 1996, and 2633 Hemoccult II containing the ODLC instructions during March, April, May, June and July 1997. All Hemoccult II were developed and read by one trained technician in the Biochemistry Laboratory (Grenoble University Hospital). RESULTS: The two populations, studied in 1996 and 1997, were strictly comparable in terms of age and number of previous screenings. Out of 6392 Hemoccult II containing the manufacturer's instructions, 157 (2.5%) were found positive, as compared to 36 (1.4%) Hemoccult II out of 2633 which contained the authors' instructions. This difference is highly significant (P = 0.001). CONCLUSION: The directions for use provided with Hemoccult II had a crucial influence on positivity rates, and therefore on the cost of screening. The instruction sheet provided by the French manufacturer is not satisfactory as it contains too much needless information, while several important pieces of advice are missing.