diff --git a/analysis/dataset_definition.py b/analysis/dataset_definition.py
index 8ca2273..fed420b 100644
--- a/analysis/dataset_definition.py
+++ b/analysis/dataset_definition.py
@@ -9,6 +9,6 @@
     index_date
 ).exists_for_patient()
 
-dataset.age = patients.age_on(index_date)
+dataset.define_population(has_registration)
 
-dataset.define_population(has_registration & (dataset.age > 17))
+dataset.sex = patients.sex