Query for logistic regression, multiple where exists - sql

Question

A logistic regression is a composed of a uniquely identifying number, followed by multiple binary variables (always 1 or 0) based on whether or not a person meets certain criteria. Below I have a query that lists several of these binary conditions. With only four such criteria the query takes a little longer to run than what I would think. Is there a more efficient approach than below? Note. tblicd is a large table lookup table with text representations of 15k+ rows. The query makes no real sense, just a proof of concept. I have the proper indexes on my composite keys.
select patient.patientid
,case when exists
(
select c.patientid from tblclaims as c
inner join patient as p on p.patientid=c.patientid
and c.admissiondate = p.admissiondate
and c.dischargedate = p.dischargedate
where patient.patientid = p.patientid
group by c.patientid
having count(*) > 1000
)
then '1' else '0'
end as moreThan1000
,case when exists
(
select c.patientid from tblclaims as c
inner join patient as p on p.patientid=c.patientid
and c.admissiondate = p.admissiondate
and c.dischargedate = p.dischargedate
where patient.patientid = p.patientid
group by c.patientid
having count(*) > 1500
)
then '1' else '0'
end as moreThan1500
,case when exists
(
select distinct picd.patientid from patienticd as picd
inner join patient as p on p.patientid= picd.patientid
and picd.admissiondate = p.admissiondate
and picd.dischargedate = p.dischargedate
inner join tblicd as t on t.icd_id = picd.icd_id
where t.descrip like '%diabetes%' and patient.patientid = picd.patientid
)
then '1' else '0'
end as diabetes
,case when exists
(
select r.patientid, count(*) from patient as r
where r.patientid = patient.patientid
group by r.patientid
having count(*) >1
)
then '1' else '0'
end
from patient
order by moreThan1000 desc

Answer 1

I would start by using subqueries in the from clause:
select q.patientid, moreThan1000, moreThan1500,
(case when d.patientid is not null then 1 else 0 end),
(case when pc.patientid is not null then 1 else 0 end)
from patient p left outer join
(select c.patientid,
(case when count(*) > 1000 then 1 else 0 end) as moreThan1000,
(case when count(*) > 1500 then 1 else 0 end) as moreThan1500
from tblclaims as c inner join
patient as p
on p.patientid=c.patientid and
c.admissiondate = p.admissiondate and
c.dischargedate = p.dischargedate
group by c.patientid
) q
on p.patientid = q.patientid left outer join
(select distinct picd.patientid
from patienticd as picd inner join
patient as p
on p.patientid= picd.patientid and
picd.admissiondate = p.admissiondate and
picd.dischargedate = p.dischargedate inner join
tblicd as t
on t.icd_id = picd.icd_id
where t.descrip like '%diabetes%'
) d
on p.patientid = d.patientid left outer join
(select r.patientid, count(*) as cnt
from patient as r
group by r.patientid
having count(*) >1
) pc
on p.patientid = pc.patientid
order by 2 desc
You can then probably simplify these subqueries more by combining them (for instance "p" and "pc" on the outer query can be combined into one). However, without the correlated subqueries, SQL Server should find it easier to optimize the queries.

Answer 2

Example of left joins as requested...
SELECT
patientid,
ISNULL(CondA.ConditionA,0) as IsConditionA,
ISNULL(CondB.ConditionB,0) as IsConditionB,
....
FROM
patient
LEFT JOIN
(SELECT DISTINCT patientid, 1 as ConditionA from ... where ... ) CondA
ON patient.patientid = CondA.patientID
LEFT JOIN
(SELECT DISTINCT patientid, 1 as ConditionB from ... where ... ) CondB
ON patient.patientid = CondB.patientID
If your Condition queries only return a maximum one row, you can simplify them down to
(SELECT patientid, 1 as ConditionA from ... where ... ) CondA