A randomized clinical study to assess the reliability and reproducibility of "Sign Grading System"

Signs such as +, ++ and +++ for mild, moderate and severe stains/calculus are being used in India effectively for more than four decades. However, there are no standardized criteria for grading, and no data regarding how and when this system was introduced, but it became very popular throughout India and is being used since then.

An attempt was made here to standardize the criteria on which the grades would be given and designate it as "Sign Grading System". Along with this, the objective of this paper was to evaluate whether this index/system satisfies all the requirements of an ideal index, particularly reliability and reproducibility.

Inter-examiner and intra-examiner reliability and reproducibility of this index was assessed through a randomized clinical study. Patients were recruited from an institutional setting by random selection from the outpatient department.

One month of training was conducted before the actual start of study. The clinical aspect of the study involved 3 investigators and 50 patients of whom 45 patients were reassessed. All the data were kept blind by a research assistant to reduce bias. Necessary measures were taken to reduce/eliminate the confounding variables, which could have affected the outcome of this study. Cohen's kappa and Fleiss' kappa statistics were employed for statistical analysis.

The index fulfills most of the ideal requirements of an index along with a high degree of reliability and reproducibility.