Initial BMI and Age calculations for PLCO

Author: Themitchell

.python-version

@@ -0,0 +1 @@
+3.13.1

docker-compose.yml

@@ -17,6 +17,7 @@ services:
       - ./lung_cancer_screening:/app/lung_cancer_screening
     restart: unless-stopped
 
+
   asset_builder:
     build:
       context: .

tests/.gitkeep …cancer_screening/calculators/__init__.pytests/.gitkeep renamed to lung_cancer_screening/calculators/__init__.py tests/.gitkeep renamed to lung_cancer_screening/calculators/__init__.py

@@ -0,0 +1,19 @@
+from decimal import Decimal, getcontext
+
+getcontext().prec = 999999
+
+class Plco:
+    AGE_COEFFICIENT = Decimal('0.0778868')
+    AGE_CENTRED_OR_REFERENT_REF_GROUP = Decimal('62')
+    BMI_COEFFICIENT = Decimal('-0.0274194')
+    BMI_CENTRED_OR_REFERENT_REF_GROUP = Decimal('27')
+
+    def __init__(self, age=None, bmi=None):
+        self.age = Decimal(str(age or 0))
+        self.bmi = Decimal(str(bmi or 0))
+
+    def age_in_years_contribution_to_estimate(self):
+        return (self.age - self.AGE_CENTRED_OR_REFERENT_REF_GROUP) * self.AGE_COEFFICIENT
+
+    def bmi_contribution_to_estimate(self):
+        return (self.bmi - self.BMI_CENTRED_OR_REFERENT_REF_GROUP) * self.BMI_COEFFICIENT

lung_cancer_screening/calculators/plco.py

@@ -0,0 +1,41 @@
+from django.test import TestCase
+from decimal import Decimal
+
+from lung_cancer_screening.calculators.plco import Plco
+
+class TestPlco(TestCase):
+    def test_age_in_years_contribution_to_estimate_when_age_is_none(self):
+        calculator = Plco(age=None)
+        result = calculator.age_in_years_contribution_to_estimate()
+
+        self.assertEqual(result, Decimal('-4.8289816'))
+
+    def test_age_in_years_contribution_to_estimate_at_74(self):
+        calculator = Plco(age=74)
+        result = calculator.age_in_years_contribution_to_estimate()
+
+        self.assertEqual(result, Decimal('0.9346416'))
+
+    def test_age_in_years_contribution_to_estimate_at_62(self):
+        calculator = Plco(age=58)
+        result = calculator.age_in_years_contribution_to_estimate()
+
+        self.assertEqual(result, Decimal('-0.3115472'))
+
+    def test_bmi_contribution_to_estimate_when_bmi_is_none(self):
+        calculator = Plco(bmi=None)
+        result = calculator.bmi_contribution_to_estimate()
+
+        self.assertEqual(result, Decimal('0.7403238'))
+
+    def test_bmi_contribution_to_estimate_when_bmi_is_23_point_5(self):
+        calculator = Plco(bmi=23.5)
+        result = calculator.bmi_contribution_to_estimate()
+
+        self.assertEqual(result, Decimal('0.0959679'))
+
+    def test_bmi_contribution_to_estimate_when_bmi_is_a_long_decimal(self):
+        calculator = Plco(bmi="26.4749212")
+        result = calculator.bmi_contribution_to_estimate()
+
+        self.assertEqual(result, Decimal('0.01439734564872'))

lung_cancer_screening/calculators/tests/__init__.py

@@ -48,6 +48,7 @@ def boolean_env(key, default=None):
     'django.contrib.staticfiles',
     'lung_cancer_screening.core',
     'lung_cancer_screening.questions'
+    'lung_cancer_screening.calculators',
 ]
 
 MIDDLEWARE = [