To assess the internal logic (content validity) of the Canadian Cardiovascular Society (CCS) scale for grading angina pectoris.
Forty-one consenting patients with stable angina of at least two months duration, admitted to a tertiary centre for coronary angiography.
Patients completed a supervised questionnaire with closed-ended questions. Key questions included: usual numbers of blocks walked on the level or flights of stairs climbed before onset of chest pain; frequency with which chest pain occurred at the usual threshold distance; presence of rest pain; and influence of modifiers suggested for class II of the scale such as walking uphill and into the wind.
Agreement of four questionnaire-defined 'stair-climbing grades' and 'walking grades' was statistically significant (P