add an elixhauser example test

Author: dewittpe

tests/test-elixhauser-example.R

@@ -0,0 +1,58 @@
+library(medicalcoder)
+
+################################################################################
+# Regression test: selected ICD-10 codes should map to specific Elixhauser
+# comorbidities under the Quan (2005) implementation. The codes were drawn from
+# the internal lookup table (get_elixhauser_codes()).
+################################################################################
+
+example_codes <-
+  data.frame(
+    patid = c("P1", "P1", "P1", "P2", "P2", "P2", "P3"),
+    icdv  = 10L,
+    dx    = 1L,
+    code  = c("I099",  # CHF
+              "I110",  # Hypertensive heart disease with heart failure (supports CHF)
+              "I132",  # Hypertensive heart and kidney disease with heart failure
+              "E109",  # Diabetes mellitus without complications
+              "E1021", # Diabetes with renal complications
+              "E6609", # Other obesity
+              "N185"   # Chronic kidney disease, stage 5 (renal failure)
+    ),
+    stringsAsFactors = FALSE
+  )
+
+res <- comorbidities(
+  data        = example_codes,
+  icd.codes   = "code",
+  id.vars     = "patid",
+  icdv.var    = "icdv",
+  dx.var      = "dx",
+  method      = "elixhauser_quan2005",
+  poa         = 1,
+  primarydx   = 0,
+  flag.method = "current"
+)
+
+res_df <- as.data.frame(res[, c("patid", "CHF", "DM", "DMCX", "OBESE", "RENLFAIL", "num_cmrb")])
+
+# P1: congestive heart failure only
+stopifnot(res_df[["CHF"]][res_df[["patid"]] == "P1"] == 1L)
+stopifnot(all(res_df[["CHF"]][res_df[["patid"]] != "P1"] == 0L))
+
+# P2: diabetes (with and without complications) + obesity
+stopifnot(res_df[["DM"]][res_df[["patid"]] == "P2"]  == 1L)
+stopifnot(res_df[["DMCX"]][res_df[["patid"]] == "P2"] == 1L)
+stopifnot(res_df[["OBESE"]][res_df[["patid"]] == "P2"] == 1L)
+
+# P3: renal failure only
+stopifnot(res_df[["RENLFAIL"]][res_df[["patid"]] == "P3"] == 1L)
+
+# Overall comorbidity counts match the manual expectation
+stopifnot(res_df[["num_cmrb"]][res_df[["patid"]] == "P1"] == 1L)
+stopifnot(res_df[["num_cmrb"]][res_df[["patid"]] == "P2"] == 3L)
+stopifnot(res_df[["num_cmrb"]][res_df[["patid"]] == "P3"] == 1L)
+
+################################################################################
+#                                 End of File                                  #
+################################################################################