epi.nomogram {epiR} | R Documentation |
Computes the post-test probability of disease given sensitivity and specificity of a test.
epi.nomogram(se, sp, pre.pos, verbose = FALSE)
se |
test sensitivity (0 - 1). |
sp |
test specificity (0 - 1). |
pre.pos |
the pre-test probability of disease in the patient. |
verbose |
logical, indicating whether detailed or summary results are to be returned. |
A list containing the following:
likelihood.ratio |
the likelihood ratio of a positive and negative test. |
prob |
the post-test probability of disease given a positive and negative test. |
Hunink M, Glasziou P (2001). Decision Making in Health and Medicine - Integrating Evidence and Values. Cambridge University Press, pp. 128 - 156.
## You are presented with a dog with lethargy, exercise intolerance, ## weight gain and bilaterally symmetric truncal alopecia. You are ## suspicious of hypothyroidism and take a blood sample to measure ## basal serum thyroxine (T4). ## You believe that around 5% of dogs presented to your clinic with ## a signalment of general debility have hypothyroidism. The serum T4 ## has a sensitivity of 0.89 and specificity of 0.85 for diagnosing ## hypothyroidism in the dog. The laboratory reports a serum T4 ## concentration of 22.0 nmol/L (reference range 19.0 to 58.0 nmol/L). ## What is the post-test probability that this dog is hypothyroid? epi.nomogram(se = 0.89, sp = 0.85, pre.pos = 0.05, verbose = FALSE) ## The post-test probability that this dog is hypothyroid is 24%.