Forms control and error detection procedures used at the Coordinating Center of the Multiple Risk Factor Intervention Trial (MRFIT).

Although methods used for data collection and quality assurance for large-scale clinical trials are important to critical reading of trial results and have been published, such reporting is the exception rather than the rule. In the MRFIT, systematic methods for processing large volumes of data over a long period of time were developed. The methods were designed to detect and control a variety of errors and to leave a complete audit trial of the processing of forms and corrections to forms. Many of these methods evolved and were refined during the course of the study as a result of trial and error. If one were to start over, the methods described herein would be modified. The field of data processing is evolving, and it is important for statistical and data processing staff of coordinating centers to recognize this and continually evaluate and update their methods. For example, the simultaneous entry and computer editing of forms is becoming more feasible with time. Also, more sophisticated intelligent data entry equipment is available for central use. Near the end of MRFIT, some data received at the Coordinating Center were entered and edited on a minicomputer. The parameter-driven edits described previously were performed at the time of data entry. Additional modifications to the content of the data dictionary for future studies are also being considered. The incorporation into the data dictionary of consistency checks (both deterministic and probabilistic) between fields on different forms would facilitate the specification of complex edit checks and would provide better documentation of the edit checks actually performed. Incorporating definitions of the numeric codes for each field would improve the documentation and facilitate reporting using statistical packages. Dedicated computer hardware should also be a major consideration of coordinating centers in future clinical trials. For MRFIT, a dedicated system was used from 1978 to the end of the trial. With the continued decline in hardware costs, dedicated systems can and should be considered, even for trials much smaller than MRFIT. We believe the system developed for processing data in the MRFIT has several advantages. It satisfies the requirements identified by Karrison or a system of data editing and control, it is largely self-documenting as a result of the data dictionary approach taken, and it is easily adaptable to other clinical studies.

Quality control in the Multiple Risk Factor Intervention Trial Nutrition Modality.

One of the principal objectives of the MRFIT was to teach and motivate participants assigned to the SI group to adhere to a fat-controlled dietary regimen over the course of the trial. The magnitude of the trial (with more than 12,000 participants, half of them assigned to the SI protocol, to be followed for at least 6 years in 22 separate centers) presented new challenges for maintenance of quality control over a nutrition intervention program. Collection of data to monitor changes in dietary intake over time in SI and UC groups, as well as information to assess dietary adherence levels in SI participants also presented large-scale challenges in maintenance of quality control. The MRFIT formulated many of its initial nutrition intervention and data collection decisions based on experience of the earlier National Diet Heart Study (NDHS). In order to avoid coding 7-day dietary records by local clinic nutritionists (as in NDHS), the trial opted for collection of 24-hour dietary recalls that were coded centrally at the Nutrition Coding Center. It necessitated extra attention to training and certification of clinic nutritionist-interviewers to be certain that NCC coders had sufficiently precise information about all foods entered on dietary recall forms. Since dietary intake data were collected over a time span of approximately 10 years, procedures for updating the food composition database and coding rules were a necessity. Continuing attention to training and monitoring of performance of clinic nutritionist-interviewers also was important. The MRFIT nutrition intervention program was designed with the need for interclinic comparability of intervention techniques in mind. This required not only development of study-wide nutrition intervention materials, but also necessitated ongoing attention to staff training and monitoring procedures in order to ensure intercenter comparability of efforts. The success of the nutrition intervention modality depended upon the continuing efforts of the nutrition counselors not only to achieve dietary adherence but also to monitor levels of dietary adherence over time. The NDHS experience served as a springboard for designing the MRFIT nutrition intervention and data collection procedures. It is hoped that techniques for maintaining and monitoring quality control over the MRFIT nutrition modality as outlined in this chapter may prove useful to future planners.