Possible error with DEX14: Among people who take drug A, how many take drug B at the same time?

[ablack3]

I think that this query is incorrect.

WITH statins AS (
SELECT descendant_concept_id AS concept_id
FROM cdm.concept_ancestor
WHERE ancestor_concept_id = 1539403
), diuretics AS (
SELECT descendant_concept_id AS concept_id
FROM cdm.concept_ancestor
WHERE ancestor_concept_id = 974166
)
SELECT COUNT(DISTINCT de1.person_id) AS num_users,
COUNT(DISTINCT de2.person_id) AS also_bp
FROM cdm.drug_exposure de1
JOIN statins s
ON de1.drug_concept_id = s.concept_id
JOIN cdm.drug_exposure de2
ON de1.person_id = de2.person_id
LEFT JOIN diuretics d
ON de2.drug_concept_id = d.concept_id
AND de2.drug_exposure_start_date < de1.drug_exposure_end_date
AND de2.drug_exposure_end_date > de1.drug_exposure_start_date;

This is my proposed fix.

WITH drug_exposure1 AS (
SELECT de.person_id,
de.drug_exposure_start_date,
de.drug_exposure_end_date
FROM cdm.drug_exposure de
INNER JOIN cdm.concept_ancestor ca
ON de.drug_concept_id = ca.descendant_concept_id
WHERE ancestor_concept_id = 1539403

),
drug_exposure2 AS (
SELECT de.person_id,
de.drug_exposure_start_date,
de.drug_exposure_end_date
FROM cdm.drug_exposure de
INNER JOIN cdm.concept_ancestor ca
ON de.drug_concept_id = ca.descendant_concept_id
WHERE ancestor_concept_id = 974166
)
SELECT COUNT(DISTINCT de1.person_id) AS num_drug1_users,
COUNT(DISTINCT de2.person_id) AS also_drug2_users
FROM drug_exposure1 de1
LEFT JOIN drug_exposure2 de2
ON de1.person_id = de2.person_id
AND de2.drug_exposure_start_date < de1.drug_exposure_end_date
AND de2.drug_exposure_end_date > de1.drug_exposure_start_date;