923 align los calculation with cms definition (#1246)

* Align LOS calculation with CMS definition: datediff + 1 (#923)

CMS defines length of stay as discharge_date - admit_date + 1, where
the admission day counts as day 1.  A same-day admit/discharge = LOS 1.
Previously datediff alone returned 0 for same-day stays.

Updated across all 9 encounter grain models and readmissions.

* Fix LOS calculation to use max(1, datediff) instead of datediff + 1

Per CMS definition, the day of admission counts but not the day of
discharge, with same-day cases counting as 1 day. The datediff already
gives the correct result for multi-day stays; only same-day (datediff=0)
needs the floor to 1. The previous datediff + 1 overcounted by 1 for
every multi-day stay. Applied across all 9 encounter grain models and
the readmissions encounter_augmented model.

Author: chase-jones

models/claims_preprocessing/encounters/final/acute_inpatient__encounter_grain.sql

@@ -157,7 +157,11 @@ select
 , tot.claim_count
 , tot.inst_claim_count
 , tot.prof_claim_count
-, {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} as length_of_stay
+, case
+    when {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} = 0
+    then 1
+    else {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }}
+  end as length_of_stay
 , case
     when c.discharge_disposition_code = '20' then 1
     else 0

models/claims_preprocessing/encounters/final/asc__encounter_grain.sql

@@ -117,7 +117,11 @@ select d.encounter_id
 , tot.encounter_type
 , tot.encounter_group
 , {{ dbt.datediff("birth_date","d.encounter_start_date","day") }} / 365 as admit_age
-, {{ dbt.datediff("d.encounter_start_date","d.encounter_end_date","day") }} as length_of_stay
+, case
+    when {{ dbt.datediff("d.encounter_start_date","d.encounter_end_date","day") }} = 0
+    then 1
+    else {{ dbt.datediff("d.encounter_start_date","d.encounter_end_date","day") }}
+  end as length_of_stay
 , e.gender
 , e.race
 , hp.diagnosis_code_type as primary_diagnosis_code_type

models/claims_preprocessing/encounters/final/emergency_department__encounter_grain.sql

@@ -152,7 +152,11 @@ select
 , tot.claim_count
 , tot.inst_claim_count
 , tot.prof_claim_count
-, {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} as length_of_stay
+, case
+    when {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} = 0
+    then 1
+    else {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }}
+  end as length_of_stay
 , case
     when c.discharge_disposition_code = '20' then 1
     else 0

models/claims_preprocessing/encounters/final/inpatient_hospice__encounter_grain.sql

@@ -145,7 +145,11 @@ select
 , tot.claim_count
 , tot.inst_claim_count
 , tot.prof_claim_count
-, {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} as length_of_stay
+, case
+    when {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} = 0
+    then 1
+    else {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }}
+  end as length_of_stay
 , case
     when c.discharge_disposition_code = '20' then 1
     else 0

models/claims_preprocessing/encounters/final/inpatient_long_term__encounter_grain.sql

@@ -146,7 +146,11 @@ select
 , tot.claim_count
 , tot.inst_claim_count
 , tot.prof_claim_count
-, {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} as length_of_stay
+, case
+    when {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} = 0
+    then 1
+    else {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }}
+  end as length_of_stay
 , case
     when c.discharge_disposition_code = '20' then 1
     else 0

models/claims_preprocessing/encounters/final/inpatient_psych__encounter_grain.sql

@@ -146,7 +146,11 @@ select
 , tot.claim_count
 , tot.inst_claim_count
 , tot.prof_claim_count
-, {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} as length_of_stay
+, case
+    when {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} = 0
+    then 1
+    else {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }}
+  end as length_of_stay
 , case
     when c.discharge_disposition_code = '20' then 1
     else 0

models/claims_preprocessing/encounters/final/inpatient_rehab__encounter_grain.sql

@@ -146,7 +146,11 @@ select
 , tot.claim_count
 , tot.inst_claim_count
 , tot.prof_claim_count
-, {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} as length_of_stay
+, case
+    when {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} = 0
+    then 1
+    else {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }}
+  end as length_of_stay
 , case
     when c.discharge_disposition_code = '20' then 1
     else 0

models/claims_preprocessing/encounters/final/inpatient_snf__encounter_grain.sql

@@ -147,7 +147,11 @@ select
 , tot.claim_count
 , tot.inst_claim_count
 , tot.prof_claim_count
-, {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} as length_of_stay
+, case
+    when {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} = 0
+    then 1
+    else {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }}
+  end as length_of_stay
 , case
     when c.discharge_disposition_code = '20' then 1
     else 0

models/claims_preprocessing/encounters/final/inpatient_substance_use__encounter_grain.sql

@@ -146,7 +146,11 @@ select
 , tot.claim_count
 , tot.inst_claim_count
 , tot.prof_claim_count
-, {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} as length_of_stay
+, case
+    when {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }} = 0
+    then 1
+    else {{ dbt.datediff("a.encounter_start_date","a.encounter_end_date","day") }}
+  end as length_of_stay
 , case
     when c.discharge_disposition_code = '20' then 1
     else 0

models/readmissions/final/readmissions__encounter_augmented.sql

@@ -16,7 +16,11 @@ select
     , aa.drg_code_type
     , aa.drg_code
     , aa.paid_amount
-    , {{ dbt.datediff("aa.admit_date", "aa.discharge_date","day") }} as length_of_stay
+    , case
+        when {{ dbt.datediff("aa.admit_date", "aa.discharge_date","day") }} = 0
+        then 1
+        else {{ dbt.datediff("aa.admit_date", "aa.discharge_date","day") }}
+      end as length_of_stay
     , case
         when bb.encounter_id is not null then 1
 	    else 0