This dataset contains longitudinal measurements of grades of aortic aneurysms, measured by ultrasound examination of the diameter of the aorta.
Format
A data frame containing 4337 rows, with each row corresponding to an ultrasound scan from one of 838 men over 65 years of age.
ptnum | (numeric) | Patient identification number |
age | (numeric) | Recipient age at examination (years) |
diam | (numeric) | Aortic diameter |
state | (numeric) | State of aneurysm. |
The states represent successive degrees of aneurysm severity, as indicated by the aortic diameter.
| State 1 | Aneurysm-free | < 30 cm |
| State 2 | Mild aneurysm | 30-44 cm |
| State 3 | Moderate aneurysm | 45-54 cm |
| State 4 | Severe aneurysm | > 55 cm |
683 of these men were aneurysm-free at age 65 and were re-screened every two years. The remaining men were aneurysmal at entry and had successive screens with frequency depending on the state of the aneurysm. Severe aneurysms are repaired by surgery.
Source
The Chichester, U.K. randomised controlled trial of screening for abdominal aortic aneurysms by ultrasonography.
References
Jackson, C.H., Sharples, L.D., Thompson, S.G. and Duffy, S.W. and Couto, E. Multi-state Markov models for disease progression with classification error. The Statistician, 52(2): 193–209 (2003)
Couto, E. and Duffy, S. W. and Ashton, H. A. and Walker, N. M. and Myles, J. P. and Scott, R. A. P. and Thompson, S. G. (2002) Probabilities of progression of aortic aneurysms: estimates and implications for screening policy Journal of Medical Screening 9(1):40–42