Objective:To study on key-factor of syndrome differentiation for damp-heat and blood stasis syndrome of akylosing spondylitis.Methods:By organically combining theories and methods of TCM syndrome differentiation with epidemiologic investigation methods and polyphyletic statistical analysis method

patients of akylosing spondylitis were selected for investigation and study

and data was statistically processed.Results:It was found by clustering analysis that main symptoms of akylosing spondylitis were limitation of lumbar spinal cord movement

morning rigidity

lumbasacral pain

pain in spinal cord and the back.Main symptoms of damp-heat and blood stasis syndrome were attained by logistic analysis

and classification of syndrome was judged.Taking prediction probability of 0.5 as judging point

the total correct rate was 88.1%.Discriminant analysis attained symptoms helpful to diagnosis of damp-heat and blood stasis syndrome

and established judging function

with conforming rate of 89.2%

sensitivity of 77.3% and specificity of 92.7%

Kappa value of 0.695.Conclusion:Application of clinical epidemiologic investigation method combined with statistical analysis to study on syndromes

including studies of key-factor of TCM disease differtentiation and syndrome differentiation

is feasible.