Lab Grading

Introduction

Within the ADLB ADaM data set there is a concept of lab grading, where there is a set of criteria for particular lab tests that grade the severity or abnormality of a lab value. The grades are from 0 to 4, where grade 0 can be viewed generally as a “NORMAL” value. The higher the grade the more severe or more abnormal the lab value is. There are several sets of lab grading criteria, currently admiral has implemented NCI-CTCAEv4, NCI-CTCAEv5 and DAIDS grading criteria. In future releases admiral may look to implement further grading criteria.

The NCI-CTCAE version 4 and 5 grading criteria can be found here: https://ctep.cancer.gov/protocoldevelopment/electronic_applications/ctc.htm .

The NCI-CTCAEv4 criteria can be found under the heading Common Terminology Criteria for Adverse Events (CTCAE)v4.0

The NCI-CTCAEv5 criteria can be found under the heading Common Terminology Criteria for Adverse Events (CTCAE)v5.0

The DAIDS grading criteria can be found here: https://rsc.niaid.nih.gov/clinical-research-sites/daids-adverse-event-grading-tables .

The DAIDS criteria can be found under the heading DAIDS Table for Grading the Severity of Adult and Pediatric Adverse Events Corrected Version 2.1

Grading metadata

admiral will store a metadata data set for each set of grading criteria in the data folder of admiral. Currently, we have atoxgr_criteria_ctcv4() for NCI-CTCAEv4, atoxgr_criteria_ctcv5() for NCI-CTCAEv5 and atoxgr_criteria_daids() for DAIDS. Each metadata data set has required variables and optional variables, the optional variables are purely for transparency, and will contain detailed information about the grading criteria. The required variables are those used by admiral to create the grade.

Structure of metadata set

The metadata data set has the following structure for the required variables:

Variable	Scope	Type	Example Value
TERM	Term describing the criteria applied to a particular lab test.	Character	“Anemia”
DIRECTION	The direction of the abnormality of a particular lab test value	Character	“L” or “H”.
SI_UNIT_CHECK	Unit of lab test, to check against input data if criteria is based on absolute values.	Character	“mmol/L”
VAR_CHECK	Comma separated list of variables used in criteria, to check input data that variables exist.	Character	“AVAL, ANRLO”
FILTER	Only required for DAIDS grading. Variable to hold code that filters the lab data based on contents of column SUBGROUP.	Character	R code that is valid within a `filter` function call.
GRADE_CRITERIA_CODE	Variable to hold code that creates grade based on defined criteria.	Character	R code that is a valid case statement within a `mutate` function call.

The metadata data set has the following structure for the optional variables:

Variable	Scope	Type	Example Value
SOC	System Organ Class the lab test belongs to.	Character	“Investigations”
SUBGROUP	Only required for DAIDS grading. Description of subgroup of lab data.	Character	“> 15 years of age”.
GRADE_1	Grade 1 criteria for lab test, normally straight from source document.	Character	“>ULN - 3.0 x ULN”.
GRADE_2	Grade 2 criteria for lab test, normally straight from source document.	Character	“>3.0 - 5.0 x ULN”.
GRADE_3	Grade 3 criteria for lab test, normally straight from source document.	Character	“>5.0 - 20.0 x ULN”.
GRADE_4	Grade 4 criteria for lab test, normally straight from source document.	Character	“>20.0 x ULN”.
DEFINITION	Definition of abnormality, normally from source document.	Character	“A finding based on laboratory test results that indicate an increase in the level of alanine aminotransferase (ALT or SGPT) in the blood specimen.”.
COMMENT	Description of any decisions made by admiral to implement grading criteria, where grading criteria alone was ambiguous.	Character	“Take worst case and assume on anticoagulation”.

Handling floating points when comparing numeric values

When comparing numeric values, for example AVAL > 1.1*ANRHI, unexpected results can occur due to floating point issues. To solve this issue {admiral} used the signif() function on both side of the equation, the number of significant digits used to compare is passed into the function derive_var_atoxgr_dir() via the argument signif_dig. Please see documentation of the function for more details and the blog post How admiral handles floating points for more context.

Creating the Lab Grade

Mapping `ADLB` to the `TERM` variable in the `{admiral}` metadata data set

library(admiral)
library(pharmaversesdtm)
library(dplyr, warn.conflicts = FALSE)
library(stringr)
library(tibble)

lb <- pharmaversesdtm::lb
adsl <- admiral::admiral_adsl

lb <- convert_blanks_to_na(lb)

Each company needs to map their lab test to a term that describes the criteria being applied. The list of terms defined in the admiral metadata to implement NCI-CTCAEv4 is below:

Likewise, the list of terms defined in the admiral metadata to implement NCI-CTCAEv5 is below: (Terms identical to NCI-CTCAEv4, except Hyperglycemia, Hyperglycemia (Fasting) and Hypophosphatemia) which are not present in NCI-CTCAEv5.

Finally, the list of terms defined in the admiral metadata to implement DAIDS is below:

Using CDISC data these lab tests can be mapped to the correct terms, firstly create PARAMCD, PARAM, AVAL, ANRLO and ANRHI, also some lab grading criteria require BASE and PCHG, so these would also need to be created before running derive_var_atoxgr_dir() function.

# Look-up tables ----

# Assign PARAMCD, PARAM, and PARAMN
param_lookup <- tibble::tribble(
  ~LBTESTCD, ~PARAMCD,  ~PARAM,                                             ~PARAMN,
  "ALB",     "ALB",     "Albumin (g/L)",                                    1,
  "ALP",     "ALKPH",   "Alkaline Phosphatase (U/L)",                       2,
  "ALT",     "ALT",     "Alanine Aminotransferase (U/L)",                   3,
  "ANISO",   "ANISO",   "Anisocytes",                                       4,
  "AST",     "AST",     "Aspartate Aminotransferase (U/L)",                 5,
  "BASO",    "BASO",    "Basophils (10^9/L)",                               6,
  "BASOLE",  "BASOLE",  "Basophils/Leukocytes (FRACTION)",                  7,
  "BILI",    "BILI",    "Bilirubin (umol/L)",                               8,
  "BUN",     "BUN",     "Blood Urea Nitrogen (mmol/L)",                     9,
  "CA",      "CA",      "Calcium (mmol/L)",                                 10,
  "CHOL",    "CHOLES",  "Cholesterol (mmol/L)",                             11,
  "CK",      "CK",      "Creatinine Kinase (U/L)",                          12,
  "CL",      "CL",      "Chloride (mmol/L)",                                13,
  "COLOR",   "COLOR",   "Color",                                            14,
  "CREAT",   "CREAT",   "Creatinine (umol/L)",                              15,
  "EOS",     "EOS",     "Eosinophils (10^9/L)",                             16,
  "EOSLE",   "EOSLE",   "Eosinophils/Leukocytes (FRACTION)",                17,
  "GGT",     "GGT",     "Gamma Glutamyl Transferase (U/L)",                 18,
  "GLUC",    "GLUC",    "Glucose (mmol/L)",                                 19,
  "HBA1C",   "HBA1C",   "Hemoglobin A1C (1)",                               20,
  "HCT",     "HCT",     "Hematocrit (1)",                                   21,
  "HGB",     "HGB",     "Hemoglobin (mmol/L)",                              22,
  "K",       "POTAS",   "Potassium (mmol/L)",                               23,
  "KETONES", "KETON",   "Ketones",                                          24,
  "LYM",     "LYMPH",   "Lymphocytes (10^9/L)",                             25,
  "LYMLE",   "LYMPHLE", "Lymphocytes/Leukocytes (FRACTION)",                26,
  "MACROCY", "MACROC",  "Macrocytes",                                       27,
  "MCH",     "MCH",     "Ery. Mean Corpuscular Hemoglobin (fmol(Fe))",      28,
  "MCHC",    "MCHC",    "Ery. Mean Corpuscular HGB Concentration (mmol/L)", 29,
  "MCV",     "MCV",     "Ery. Mean Corpuscular Volume (f/L)",               30,
  "MICROCY", "MICROC",  "Microcytes",                                       31,
  "MONO",    "MONO",    "Monocytes (10^9/L)",                               32,
  "MONOLE",  "MONOLE",  "Monocytes/Leukocytes (FRACTION)",                  33,
  "PH",      "PH",      "pH",                                               34,
  "PHOS",    "PHOS",    "Phosphate (mmol/L)",                               35,
  "PLAT",    "PLAT",    "Platelet (10^9/L)",                                36,
  "POIKILO", "POIKIL",  "Poikilocytes",                                     37,
  "POLYCHR", "POLYCH",  "Polychromasia",                                    38,
  "PROT",    "PROT",    "Protein (g/L)",                                    39,
  "RBC",     "RBC",     "Erythrocytes (TI/L)",                              40,
  "SODIUM",  "SODIUM",  "Sodium (mmol/L)",                                  41,
  "SPGRAV",  "SPGRAV",  "Specific Gravity",                                 42,
  "TSH",     "TSH",     "Thyrotropin (mU/L)",                               43,
  "URATE",   "URATE",   "Urate (umol/L)",                                   44,
  "UROBIL",  "UROBIL",  "Urobilinogen",                                     45,
  "VITB12",  "VITB12",  "Vitamin B12 (pmol/L)",                             46,
  "WBC",     "WBC",     "Leukocytes (10^9/L)",                              47
)

adlb <- lb %>%
  ## Add PARAMCD PARAM and PARAMN - from LOOK-UP table
  derive_vars_merged_lookup(
    dataset_add = param_lookup,
    new_vars = exprs(PARAMCD, PARAM, PARAMN),
    by_vars = exprs(LBTESTCD)
  ) %>%
  ## Calculate PARCAT1 AVAL AVALC ANRLO ANRHI
  ## Dummy the values for BASE
  mutate(
    PARCAT1 = LBCAT,
    AVAL = LBSTRESN,
    AVALC = ifelse(
      is.na(LBSTRESN) | as.character(LBSTRESN) != LBSTRESC,
      LBSTRESC,
      NA
    ),
    ANRLO = LBSTNRLO,
    ANRHI = LBSTNRHI,
    BASE = AVAL - 10
  )
#> All `LBTESTCD` are mapped.

Another look-up table is used to add on ATOXDSCL and ATOXDSCH using PARAMCD. ATOXDSCL holds the terms for grading low lab values, and ATOXDSCH holds the terms for grading high lab values. The names of these variables can be user-defined. ATOXDSCL and ATOXDSCH are the link from ADLB data to the admiral metadata that holds the grading criteria.

# Assign ATOXDSCL and ATOXDSCH to hold lab grading terms
# ATOXDSCL and ATOXDSCH hold terms defined by NCI-CTCAEv4.
grade_lookup <- tibble::tribble(
  ~PARAMCD, ~ATOXDSCL,                    ~ATOXDSCH,
  "ALB",    "Hypoalbuminemia",            NA_character_,
  "ALKPH",  NA_character_,                "Alkaline phosphatase increased",
  "ALT",    NA_character_,                "Alanine aminotransferase increased",
  "AST",    NA_character_,                "Aspartate aminotransferase increased",
  "BILI",   NA_character_,                "Blood bilirubin increased",
  "CA",     "Hypocalcemia",               "Hypercalcemia",
  "CHOLES", NA_character_,                "Cholesterol high",
  "CK",     NA_character_,                "CPK increased",
  "CREAT",  NA_character_,                "Creatinine increased",
  "GGT",    NA_character_,                "GGT increased",
  "GLUC",   "Hypoglycemia",               "Hyperglycemia",
  "HGB",    "Anemia",                     "Hemoglobin increased",
  "POTAS",  "Hypokalemia",                "Hyperkalemia",
  "LYMPH",  "CD4 lymphocytes decreased",  NA_character_,
  "PHOS",   "Hypophosphatemia",           NA_character_,
  "PLAT",   "Platelet count decreased",   NA_character_,
  "SODIUM", "Hyponatremia",               "Hypernatremia",
  "WBC",    "White blood cell decreased", "Leukocytosis",
)

adlb <- adlb %>%
  derive_vars_merged(
    dataset_add = grade_lookup,
    by_vars = exprs(PARAMCD),
  )

It is now straightforward to create the grade, for low lab values the grade will be held in ATOXGRL and for high lab values the grade will be held in ATOXGRH.

Note: for NCICTCAEv5 grading, you would update meta_criteria parameter to atoxgr_criteria_ctcv5 and for DAIDS grading you would update meta_criteria parameter to atoxgr_criteria_daids

adlb <- adlb %>%
  derive_var_atoxgr_dir(
    new_var = ATOXGRL,
    tox_description_var = ATOXDSCL,
    meta_criteria = atoxgr_criteria_ctcv4,
    criteria_direction = "L",
    get_unit_expr = extract_unit(PARAM)
  ) %>%
  derive_var_atoxgr_dir(
    new_var = ATOXGRH,
    tox_description_var = ATOXDSCH,
    meta_criteria = atoxgr_criteria_ctcv4,
    criteria_direction = "H",
    get_unit_expr = extract_unit(PARAM)
  )

Note: admiral does not grade ‘Anemia’ or ‘Hemoglobin Increased’ because the metadata is based on the SI unit of ‘g/L’, however the CDISC data has SI unit of ‘mmol/L’. Please see SI_UNIT_CHECK variable in admiral metadata atoxgr_criteria_ctcv4() or atoxgr_criteria_ctcv5() or atoxgr_criteria_daids(), the metadata is in the data folder of admiral.

admiral also gives the option to combine ATOXGRL and ATOXGRH into one variable, namely ATOXGR. Grades held in ATOXGRL will be given a negative value in ATOXGR to distinguish between low and high values.

adlb <- adlb %>%
  derive_var_atoxgr()

NCI-CTCAEV4 implementation

Terms graded

Grading is implemented for those lab tests where a lab value is included in the grading definition, admiral does NOT try to read any other data to determine the grade, and only the ADLB dataset is used. The following CTCAE v4.0 SOC values were identified for grading, these are “Investigations”, “Metabolism and nutrition disorders” and “Blood and lymphatic system disorders”.

From these SOC values the following terms criteria is implemented in admiral

From SOC = “Investigations” there are 21 CTCAE v4.0 Terms:

Activated partial thromboplastin time prolonged
Alanine aminotransferase increased
Alkaline phosphatase increased
Aspartate aminotransferase increased
Blood bilirubin increased
CD4 lymphocytes decreased
Cholesterol high
CPK increased
Creatinine increased
Fibrinogen decreased
GGT increased
Haptoglobin decreased
Hemoglobin increased
INR increased
Lipase increased
Lymphocyte count decreased
Lymphocyte count increased
Neutrophil count decreased
Platelet count decreased
Serum amylase increased
White blood cell decreased

From the SOC = “Metabolism and nutrition disorders” there are 14 CTCAE v4.0 Terms:

Hypercalcemia
Hyperglycemia
Hyperkalemia
Hypermagnesemia
Hypernatremia
Hypertriglyceridemia
Hyperuricemia
Hypoalbuminemia
Hypocalcemia
Hypoglycemia
Hypokalemia
Hypomagnesemia
Hyponatremia
Hypophosphatemia

From the SOC = “Blood and lymphatic system disorders” there are 2 CTCAE v4.0 Terms:

Anemia
Leukocytosis

Updates made to TERM

For terms “Hypocalcemia” and “Hypercalcemia” the criteria is provided for Calcium and Ionized Calcium, therefore admiral created a row for each in the metadata, this is noted in the COMMENT variable of the metadata:

Similarly, there is criteria applicable to Fasting Glucose as well as non-Fasting Glucose for “Hyperglycemia” so again this was split into 2 rows, and noted in the COMMENT variable. Note “Hypoglycemia” does not require to be split into 2 rows:

Assumptions made when grading

For term “INR Increased” there is the following criteria:

admiral assumed worst case and used both parts of the criteria for grading, so comparing lab value against ULN and also BASE. The decision made was put in the COMMENT field.

For TERM “Hyperuricemia”, the criteria for Grade 1 and Grade 3 is the same with respect to the lab value, so worse case is assumed as grade 3. The decision made was put in the COMMENT field.

A similar approach was taken for TERM “Hypokalemia” where Grade 1 and Grade 2 criteria is the same with respect to the lab value, so worse case is assumed as grade 2. The decision made was put in the COMMENT field.

NCI-CTCAEV5 implementation

Terms graded

Grading is implemented for those lab tests where a lab value is included in the grading definition, admiral does NOT try to read any other data to determine the grade, and only the ADLB dataset is used. The following CTCAE v5.0 SOC values were identified for grading, these are “Investigations”, “Metabolism and nutrition disorders” and “Blood and lymphatic system disorders”.

From these SOC values the following terms criteria is implemented in admiral

From SOC = “Investigations” there are 21 CTCAE v5.0 Terms:

Activated partial thromboplastin time prolonged
Alanine aminotransferase increased
Alkaline phosphatase increased
Aspartate aminotransferase increased
Blood bilirubin increased
CD4 lymphocytes decreased
Cholesterol high
CPK increased
Creatinine increased
Fibrinogen decreased
GGT increased
Haptoglobin decreased
Hemoglobin increased
INR increased
Lipase increased
Lymphocyte count decreased
Lymphocyte count increased
Neutrophil count decreased
Platelet count decreased
Serum amylase increased
White blood cell decreased

Note: These are the same terms identified for NCI-CTCAEv4.

From the SOC = “Metabolism and nutrition disorders” there are 12 CTCAE v4.0 Terms:

Hypercalcemia
Hyperkalemia
Hypermagnesemia
Hypernatremia
Hypertriglyceridemia
Hyperuricemia
Hypoalbuminemia
Hypocalcemia
Hypoglycemia
Hypokalemia
Hypomagnesemia
Hyponatremia

Note: These are the same terms identified for NCI-CTCAEv4, except “Hypophosphatemia” and “Hyperglycemia” which are not in NCICTCAEv5 grading criteria.

From the SOC = “Blood and lymphatic system disorders” there are 2 CTCAE v4.0 Terms:

Anemia
Leukocytosis

Note: These are the same terms identified for NCI-CTCAEv4.

Updates made to TERM

Assumptions made when grading

For terms “Alanine aminotransferase increased”, “Alkaline phosphatase increased”, “Aspartate aminotransferase increased”, “Blood bilirubin increased” and “GGT increased” the criteria is dependent on the Baseline Value BASE being normal or abnormal. For BASE to be abnormal we compare it with the Upper Limit of Normal (ULN) ANRHI, i.e. BASE > ANRHI. This means if BASE is abnormal then the grade is always zero for the baseline observation.

For term “INR Increased” there is the following criteria:

admiral assumed worst case and used both parts of the criteria for grading, so comparing lab value against ULN and also BASE. The decision made was put in the COMMENT field.

Similarly, for terms “Lipase Increased” and “Serum amylase increased” there is the following criteria:

admiral assumed worst case and implemented highest grade possible. The decision made was put in the COMMENT field.

For TERM “Hyperuricemia”, the criteria for Grade 1 and Grade 3 is the same with respect to the lab value, so worse case is assumed as grade 3. The decision made was put in the COMMENT field.

A similar approach was taken for TERM “Hypokalemia” and “Hyponatremia”. For “Hypokalemia”, where Grade 1 and Grade 2 criteria is the same with respect to the lab value, then worse case is assumed as grade 2. For “Hyponatremia”, where Grade 2 and Grade 2 criteria is the same with respect to the lab value, then worse case is assumed as grade 3. The decision made was put in the COMMENT field.

DAIDS implementation

Terms graded

Grading is implemented for those lab tests where a lab value is included in the grading definition, admiral does NOT try to read any other data to determine the grade, and only the ADLB dataset is used. The following DAIDS SOC values were identified for grading, these are “Chemistries” and “Hematology”.

From these SOC values the following terms criteria is implemented in admiral

From SOC = “Chemistries” there are 31 DAIDS Terms:

Acidosis
Albumin, Low
Alkaline Phosphatase, High
Alkalosis
ALT, High
Amylase, High
AST, High
Bicarbonate, Low
Direct Bilirubin, High
Total Bilirubin, High
Calcium, High
Calcium (Ionized), High
Calcium, Low
Calcium (Ionized), Low
Creatine Kinase, High
Creatinine, High
Glucose Fasting, High
Glucose Nonfasting, High
Glucose, Low
Lactate, High
Lipase, High
Cholesterol, Fasting, High
LDL, Fasting, High
Triglycerides, Fasting, High
Magnesium, Low
Phosphate, Low
Potassium, High
Potassium, Low
Sodium, High
Sodium, Low
Uric Acid, High

Note: {admiral} does not grade for TERM = “Total Bilirubin, High” when AGE <= 28 days, these criteria are in Appendix of DAIDS Table for Grading the Severity of Adult and Pediatric Adverse Events Corrected Version 2.1.

From the SOC = “Hematology” there are 11 DAIDS Terms:

Absolute CD4+ Count, Low
Absolute Lymphocyte Count, Low
Absolute Neutrophil Count (ANC), Low
Fibrinogen Decreased
Hemoglobin, Low
INR, High
Methemoglobin
PTT, High
Platelets, Decreased
PT, High
WBC, Decreased

Terms with age or sex dependent grading criteria

Some terms defined in DAIDS have age or sex dependent grading criteria, {admiral} handles this in variable FILTER in the metadata. We use {admiral} function compute_duration to calculate age, see TERM = “Cholesterol, Fasting, High”:

Note: All possible values must be covered for each TERM defined, for TERM = “Absolute Lymphocyte Count, Low” and “Absolute CD4+ Count, Low” there is only grading criteria defined for age > 5 years. Therefore, we add another row with age <= 5 years and set grade to missing. Similarly, for TERM = “LDL, Fasting, High” there is only grading criteria defined for age > 2 years. Therefore, we add another row with age <= 2 years and set grade to missing.

Assumptions made when grading

For terms “INR, High”, “PT, High” and “PTT, High”, the criteria is based on subjects “not on anticoagulation therapy”, this is captured in COMMENT field.

Similarly, for terms “Absolute CD4+ Count, Low” and “Absolute Lymphocyte Count, Low”, the criteria is based on subjects “not HIV infected”, this is captured in COMMENT field.

For term “Acidosis”, “Alkalosis” and “Direct Bilirubin, High (> 28 days of age)”, {admiral} grades as high as possible, so assumes worst case and subject has “life-threatening consequences”. This is captured in COMMENT field.

Similarly, for term “Lactate, High”, {admiral} only grade 1 and 2, and there is the following criteria:

admiral assumed worst case and assume “without acidosis”. The decision made was put in the COMMENT field.

For TERM “Direct Bilirubin, High (<= 28 days of age)” and “Uric Acid, High” the criteria is not given in SI unit. The conversion to SI unit is in the comment field.

Conclusion

With NCI-CTCAEv4, NCI-CTCAEv5 and DAIDS grading now implemented, {admiral} may look to implement other industry standard grading criteria. Providing tools for users to easily interact with the metadata to update criteria, based on their companies needs will also be looked at. Ideally, users should be able to create their own metadata for company specific grading schemes.

Introduction

Grading metadata

Structure of metadata set

Handling floating points when comparing numeric values

Creating the Lab Grade

Mapping ADLB to the TERM variable in the {admiral} metadata data set

NCI-CTCAEV4 implementation

Terms graded

Updates made to TERM

Assumptions made when grading

NCI-CTCAEV5 implementation

Terms graded

Updates made to TERM

Assumptions made when grading

DAIDS implementation

Terms graded

Terms with age or sex dependent grading criteria

Assumptions made when grading

Conclusion

Mapping `ADLB` to the `TERM` variable in the `{admiral}` metadata data set