The calculator in question is the American Society of Transplantation Infectious Diseases Community of Practice histological classification of BK polyomavirus-associated nephropathy, also known as the AST-IDCOP classification. This scoring system is specifically used in the patient population of kidney transplant recipients. The clinical utility of this calculator is to classify the severity of BK polyomavirus-associated nephropathy, a significant complication post-kidney transplantation that can lead to graft loss. The AST-IDCOP classification helps in guiding the management and treatment of these patients, and in predicting their prognosis. There are no specific exclusion criteria for its use, but it is most relevant in patients who have undergone kidney transplantation and are suspected or confirmed to have BK polyomavirus-associated nephropathy.

American Society of Transplantation Infectious Diseases Community of Practice histological classification of BK polyomavirus-associated nephropathy (AST‐IDCOP classification)

# Criteria
 ## Viral cytopathic changes
A. <= 10%
B. 11‐25%
C. 26-50%
D. > 50%
## Interstitial inflammation
E. <= 10%
F. 11‐25%
G. 26-50%
H. > 50%
## Tubular atrophy
I. <= 10%
J. 11-50%
K. > 50%
## Interstitial fibrosis
L. <= 10%
M. 11-50%
N. > 50%

# Conditions
- (A or B) and E and I and L
- (B or C) and F and (I or J) and (L or M)
- (B or C) and G and (I or J) and (L or M)
- (B or C) and H and (I or J) and (L or M)
- (A or B or C or D) and (E or F or G or H) and K and N
- true