Estimate risk of cardiovascular events using the American Heart Association (AHA) Predicting Risk of cardiovascular disease EVENTs (PREVENT) equations.

estimate_risk() and est_risk() are the same function, with the latter being a literal copy of the former just for those who favor syntactical brevity (i.e., a function synonym).

Estimation includes both 10- and 30-year risk of 5 events:

Total cardiovascular disease (CVD)
- This outcome includes atherosclerotic CVD (ASCVD) and heart failure as defined below
ASCVD
- This outcome includes coronary heart disease (CHD) and stroke as defined below
Heart failure (often abbreviated HF, but not herein)
CHD
- This outcome includes nonfatal myocardial infarction (MI) and fatal CHD
Stroke

See also the README for this package, which goes into additional detail about the PREVENT equations (site, GitHub).

Usage

estimate_risk(
  age,
  sex,
  sbp,
  bp_tx,
  total_c,
  hdl_c,
  statin,
  dm,
  smoking,
  egfr,
  bmi,
  hba1c = NULL,
  uacr = NULL,
  zip = NULL,
  model = NULL,
  time = "both",
  chol_unit = "mg/dL",
  optional_strict = FALSE,
  quiet = FALSE
)

est_risk(
  age,
  sex,
  sbp,
  bp_tx,
  total_c,
  hdl_c,
  statin,
  dm,
  smoking,
  egfr,
  bmi,
  hba1c = NULL,
  uacr = NULL,
  zip = NULL,
  model = NULL,
  time = "both",
  chol_unit = "mg/dL",
  optional_strict = FALSE,
  quiet = FALSE
)

Arguments

age: Numeric (required predictor variable): Age in years, from 30-79
sex: Character (required predictor variable): Either "female" or "male" ("f" and "m" are accepted abbreviations)
sbp: Numeric (required predictor variable): Systolic blood pressure (SBP) in mmHg, from 90-180; see the "Details" section for more information about the upper bound of the range
bp_tx: Logical or numeric equivalent (required predictor variable): Whether the person is on blood pressure treatment, either TRUE or FALSE (1 or 0 are accepted as alternative input)
total_c: Numeric (required predictor variable): Total cholesterol in mg/dL or mmol/L (see chol_unit argument), from 130-320 (for chol_unit = "mg/dL") or 3.36-8.28 (for chol_unit = "mmol/L")
hdl_c: Numeric (required predictor variable): High-density lipoprotein cholesterol (HDL-C) in mg/dL or mmol/L (see chol_unit argument), from 20-100 (for chol_unit = "mg/dL") or 0.52-2.59 (for chol_unit = "mmol/L")
statin: Logical or numeric equivalent (required predictor variable): Whether the person is taking a statin, either TRUE or FALSE (1 or 0 are accepted as alternative input)
dm: Logical or numeric equivalent (required predictor variable): Whether the person has diabetes mellitus (DM), either TRUE or FALSE (1 or 0 are accepted as alternative input)
smoking: Logical or numeric equivalent (required predictor variable): Whether the person is currently smoking (which PREVENT defines as cigarette use within the last 30 days), either TRUE or FALSE (1 or 0 are accepted as alternative input)
egfr: Numeric or call (required predictor variable): Estimated glomerular filtration rate (eGFR) in mL/min/1.73m², entered either as a numeric from 15-140 or as a call to calc_egfr() or synonyms, as described in the "Details" section
bmi: Numeric or call (required predictor variable): Body mass index (BMI) in kg/m², entered either as a numeric from 18.5-39.9 or as a call to calc_bmi() or synonyms, as described in the "Details" section
hba1c: Numeric (optional predictor variable): Glycated hemoglobin (HbA1c) in %, from 4.5-15; see the "Details" section for more information about the lower bound of the range
uacr: Numeric (optional predictor variable): Urine albumin-to-creatinine ratio (UACR) in mg/g, from 0.1-25000
zip: Character (optional predictor variable): ZIP code of the person's residence, used to estimate the Social Deprivation Index (SDI); see the "Details" section for more information
model: Character (required, but has default): The PREVENT model to use, one of NULL (the default), "base" (the base model), "hba1c" (the base model adding HbA1c), "uacr" (the base model adding UACR), "sdi" (the base model adding SDI), or "full" (the base model adding HbA1c, UACR, and SDI). If NULL, the model will be determined by algorithm specified in the "Details" section, and this is the intended argument for most users. The ability to specify mainly exists for specific use cases (e.g., research purposes).
time: Character or numeric (required, but has default): Whether to estimate risk over 10 or 30 years, one of "both" (character; the default); 10 (numeric), "10" (character), or "10yr" (character); or 30 (numeric), "30" (character), or "30yr" (character); if estimating over 30 years and age > 59, a warning will accompany the results regarding the reliability of the estimation (see the "Value" section for more information)
chol_unit: Character (required, but has default): The unit of measurement for total_c and hdl_c, either "mg/dL" (the default) or "mmol/L" ("mg" and "mmol" are accepted abbreviations)
optional_strict: Logical (required, but has default): Whether to enforce strictness on optional predictor variables, either TRUE or FALSE (the default). The argument itself is strict, so 1 or 0 are not accepted (in contrast with some of the other logical inputs considered by this function), and moreover, anything other than TRUE will be treated as FALSE. If FALSE, the function will discard invalid optional predictor variables but still allow the model to run. If TRUE, optional predictor variables entered (if any) must be valid for the function to return risk estimates. See the "Value" section for more information.
quiet: Logical (required, but has default): Whether to suppress messages and warnings in the console, either TRUE or FALSE (the default); this argument is strict, so 1 or 0 are not accepted (in contrast with some of the other logical inputs considered by this function), and moreover, anything other than TRUE will be treated as FALSE

Value

estimate_risk() will always return a data frame as a tibble, and all references herein to a data frame being returned are for a data frame as a tibble (see the tibble package for more detail). However, the manner in which the data frame is returned will come in one of two ways, depending on the time argument:

When time = "both": A list of length 2, with each item in the list being a data frame containing the 10-year and 30-year estimates, in that order
Otherwise: A single data frame containing the risk estimate for the specified time horizon

The data frame will have the following columns:

total_cvd: The estimated risk of a total CVD event (column type: double)
ascvd: The estimated risk of an ASCVD event (column type: double)
heart_failure: The estimated risk of a HF event (column type: double)
chd: The estimated risk of a CHD event (column type: double)
stroke: The estimated risk of a stroke event (column type: double)
model: The PREVENT model used (column type: character)
over_years: The time horizon for the risk estimate (column type: integer)
input_problems: Semicolon-separated vector of length one delineating input problems, if any exist; otherwise, NA_character_ (column type: character)

When valid input parameters exist for all required predictor variables

The risk estimate columns are all of type double, and they are presented as a proportion rounded to 3 decimal places. Halves are rounded up to align with what many people likely expect, but this is in contrast to base R's default rounding behavior (it is a perfectly reasonable default, but perhaps somewhat unexpected for people who are not familiar with different standards/conventions for rounding; see round() for further detail).

The model column will be of type character, taking one of the following values: "base", "hba1c", "uacr", "sdi", or "full".

The over_years column will be of type integer, either 10 or 30.

If optional_strict = TRUE, the above will only hold if the optional predictor variables that are entered (if any) are valid; if any optional variables are entered but are invalid, the function will behave in the same manner as when invalid input parameters exist for one or more required variables.

When invalid input parameters exist for one or more required predictor variable(s)

The function will issue a warning about the problematic variables, unless quiet = FALSE. A data frame will be returned with the following characteristics:

All risk estimates will be set to NA_real_
The model column will state "none"
The over_years column will be set to NA_integer_
The input_problems column will contain a character vector of length 1 delineating the problematic variable(s); if multiple problematic variables exist, they will be separated by semicolons

When invalid input parameters exist for one or more optional predictor variable(s)

When `optional_strict = TRUE`

The function will behave similarly to when invalid input parameters exist for one or more required variables, with the input_problems column delineating the problematic variables

When `optional_strict = FALSE`

The function will issue a warning about the problematic variables, unless quiet = FALSE. The problematic optional variables will then be functionally discarded and the PREVENT equations still run, in accordance with the specifications detailed in the "Details" section regarding model selection. A data frame will be returned with the following characteristics:

All estimates will be returned as specified in the valid input parameters section, as will the model and over_years columns
The input_problems column will contain a character vector of length 1 delineating the problematic variables (because optional predictor variables are allowed to be empty, any input that is functionally empty or missing (such as NULL, numeric(0), NA, etc.) will not be considered problematic and thus not populate in the input_problems column)

When estimating 30-year risk and age > 59

The function advises 30-year risk prediction for people > 59 years is questionable via two warnings:

in the console (that can be suppressed by setting quiet = TRUE)
in the column input_problems of the return tibble (quiet has no impact here)

The special case of the `zip` argument

The above rule for optional predictor variables applies to the zip argument as well, but with the additional reminder that there are valid zip codes that do not have an SDI score. This is importantly different from an invalid input for zip. See the "Details" section for more information about how this is handled, but users should not expect anything to populate in the input_problems column if the zip is valid, regardless of whether that zip has an SDI score. As will be clear from the "Details" section, users will be able to determine when a zip code does not have an SDI score based on the model that was used.

Combining output into a single data frame

The output when time = "both" is a list of data frames, one for each time horizon, but if desired, it is easy to combine these into a single data frame, e.g.:


  res_base_r <- do.call(rbind, res)        # Combine in base R
  res_dplyr <- dplyr::bind_rows(res)       # Combine in dplyr
  res_dt <- data.table::rbindlist(res)     # Combine in data.table

  # These all yield the same tabular output, but the attributes vary
  # (e.g., base R adds row names)

  all.equal(res_base_r, res_dplyr, check.attributes = FALSE)   # TRUE
  all.equal(res_dplyr, res_dt, check.attributes = FALSE)       # TRUE

Details

Why is the upper limit of the SBP range 180 mmHg?

Some may notice the upper limit is set to 180 mmHg here, whereas the PREVENT equations technically permit up to 200 mmHg. The Pooled Cohort Equations (PCEs) do this as well. I have restricted to 180 mmHg, as SBP beyond 180 mmHg constitutes hypertensive urgency (per AHA's own definitions), and irrespective of the debate surrounding labels like hypertensive urgency and emergency, it would seem clinically unreasonable to engage with the PREVENT equations when someone has more pressing matters to address (better blood pressure control per se).

Why is the lower limit of the HbA1c 4.5%?

Some may notice the lower limit is set to 4.5% here, whereas the PREVENT equations technically permit down to 3%. I have restricted to 4.5%, as HbA1c of 3% is neither realistic nor safe for a person. For example, using the HbA1c to estimated average glucose (eAG) converter from the American Diabetes Association (https://professional.diabetes.org/glucose_calc), a HbA1c of 3% corresponds to an eAG of 39 mg/dL (2.2 mmol/L).

Entering eGFR and BMI as a call rather than a numeric value

The eGFR and bmi arguments can be entered as numeric values or as calls to calc_egfr() and calc_bmi(), respectively. They both have synonyms as well:

Synonyms for calc_egfr() are calculate_egfr(), calc_ckd_epi(), and calculate_ckd_epi(), with the latter two synonyms reflecting the calculation is from the CKD-EPI equations (the reparameterized version without race, which is also what the PREVENT equations use).
The synonym for calc_bmi() is calculate_bmi().

These convenience functions add value where a person might have the necessary components to calculate the respective parameter but do not have handy the parameter itself.

Although these convenience functions were, of course, tested for accuracy, they were written and tested within the context of supporting the PREVENT equations as implemented within this package. As such, they are not exported, and users will be warned to proceed with caution if they try to use these functions outside of estimate_risk() or its synonym est_risk().

The syntax for these convenience functions is as follows:

calc_egfr(cr, units = "mg/dL", age, sex, quiet = FALSE)
- cr is the creatinine in whatever units are specified by units
- units is the unit of measurement for cr, either "mg/dL" or "umol/L", with "mg" and "umol" being accepted abbreviations
- age is the age of the person, but there is no need to enter this, as the function will extract this from the age argument of estimate_risk(); in fact, any argument entered here will be ignored in favor of the age argument of estimate_risk()
- sex is the sex of the person, but there is no need to enter this, as the function will extract this from the sex argument of estimate_risk(); in fact, any argument entered here will be ignored in favor of the sex argument of estimate_risk()
- quiet is a logical indicating whether to suppress the warning about use outside of estimate_risk()
- An example call would be calc_egfr(1.2) (because units defaults to "mg/dL") or calc_egfr(88, "umol")
calc_bmi(weight, height, units = "nonmetric", quiet = FALSE)
- weight is the weight in pounds if units = "nonmetric" or kilograms if units = "metric"
- height is the height in inches if units = "nonmetric" or centimeters if units = "metric"
- units is the unit of measurement for weight and height, either "nonmetric" or "metric"
- quiet is a logical indicating whether to suppress the warning about use outside of estimate_risk()
- An example call would be calc_bmi(150, 70) (because units defaults to "nonmetric") or calc_bmi(68, 178, "metric")

Read more from the Robert Graham Center's page on the SDI (https://www.graham-center.org/maps-data-tools/social-deprivation-index.html)

Model selection when `model = NULL`

If model = NULL, the model will be determined by the following algorithm:

If no optional predictor variables (HbA1c, UACR, zip code) are entered, or only invalid optional variables are entered and optional_strict = FALSE: The base model
If one of the optional predictor variables is entered, or two or more optional predictor variables are entered but only one is valid and optional_strict = FALSE: The base model adding that variable (e.g., if HbA1c is entered and no other optional predictor variables are entered, the base model adding HbA1c; if HbA1c and UACR are entered, but HbA1c is invalid and optional_strict = FALSE, the base model adding UACR)
If two or more of the optional predictor variables are entered, or all three optional variables are entered but one is invalid and optional_strict = FALSE: The full model (the PREVENT equations include a term for optional predictor variables being missing, so if one of the optional predictor variables is missing in this scenario, it is treated as such within the full model)

What if SDI is not available for a zip code?

Some zip codes do not have SDI data available, and the PREVENT equations include a term for SDI being missing. As such, if a user enters a valid zip code but no SDI data are available, the user will be notified, and the tool will then implement the missing term as part of predicting risk whenever the full model is used, but SDI will otherwise be removed from prediction. Specifically, the following models will predict risk in the situation where the user enters a valid zip code, but no SDI data are available:

If the user does not enter a valid HbA1c or UACR: The base model
If the user enters valid HbA1c and UACR: The full model (treating SDI as missing)
If the user enters a valid HbA1c: The base model adding HbA1c
If the user enters a valid UACR: The base model adding UACR

Examples

# Example with all required predictor variables (example from Table S25
# in the supplemental PDF appendix of the PREVENT equations article)
#
# Optional predictor variables are all omitted (and thus take their default)
# `model` is also omitted (and thus takes its default, with the function selecting
# the model based on the algorithm specified in the "Details" section)
# `time` is also omitted (and thus takes its default, with the function returning
# estimates for both 10- and 30-year risk as specified in the "Value" section)
#
# Expect the base model to run given absence of optional predictor variables.
res <- estimate_risk(
  age = 50, 
  sex = "female",    # or "f"
  sbp = 160, 
  bp_tx = TRUE,      # or 1
  total_c = 200,     # default unit is "mg/dL"
  hdl_c = 45,        # default unit is "mg/dL"
  statin = FALSE,    # or 0
  dm = TRUE,         # or 1
  smoking = FALSE,   # or 0
  egfr = 90,
  bmi = 35
)
#> Estimates are from: Base model.

# Based on Table S25, expect the 10-year risk for `total_cvd` to be 0.147.
# Based on the supplemental Excel file, also expect:
# 10-year risks: `ascvd`, 0.092; `heart_failure`, 0.081; 
# `chd`, 0.044; `stroke`, 0.054
# 30-year risks: `total_cvd`, 0.53; `ascvd`, 0.354; `heart_failure`, 0.39;
# `chd`, 0.198; `stroke`, 0.221
res
#> $risk_est_10yr
#> # A tibble: 1 × 8
#>   total_cvd ascvd heart_failure   chd stroke model over_years input_problems
#>       <dbl> <dbl>         <dbl> <dbl>  <dbl> <chr>      <int> <chr>         
#> 1     0.147 0.092         0.081 0.044  0.054 base          10 NA            
#> 
#> $risk_est_30yr
#> # A tibble: 1 × 8
#>   total_cvd ascvd heart_failure   chd stroke model over_years input_problems
#>       <dbl> <dbl>         <dbl> <dbl>  <dbl> <chr>      <int> <chr>         
#> 1      0.53 0.354          0.39 0.198  0.221 base          30 NA            
#> 
 
# Example with HbA1c 
# (also changing required predictor variables & limiting to 10-year results)
estimate_risk(
  age = 66, 
  sex = "male",      # or "m"
  sbp = 148, 
  bp_tx = FALSE,     
  total_c = 188,     
  hdl_c = 52,        
  statin = TRUE,    
  dm = TRUE,         
  smoking = TRUE,   
  egfr = 67,
  bmi = 30,
  hba1c = 7.5,
  time = "10yr"      # only 10-year results will show
)
#> Estimates are from: Base model adding HbA1c.
#> # A tibble: 1 × 8
#>   total_cvd ascvd heart_failure   chd stroke model over_years input_problems
#>       <dbl> <dbl>         <dbl> <dbl>  <dbl> <chr>      <int> <chr>         
#> 1     0.231 0.142         0.149 0.082  0.071 hba1c         10 NA            

# Example with UACR (limited to 30-year results)
estimate_risk(
  age = 66, 
  sex = "female",   
  sbp = 148, 
  bp_tx = FALSE,     
  total_c = 188,     
  hdl_c = 52,        
  statin = TRUE,    
  dm = TRUE,         
  smoking = TRUE,   
  egfr = 67,
  bmi = 30,
  uacr = 750,
  time = "30yr"      # only 30-year results will show    
)
#> Estimates are from: Base model adding UACR.
#> Warning: Estimating 30-year risk in people > 59 years of age is questionable
#> # A tibble: 1 × 8
#>   total_cvd ascvd heart_failure   chd stroke model over_years input_problems    
#>       <dbl> <dbl>         <dbl> <dbl>  <dbl> <chr>      <int> <chr>             
#> 1     0.562 0.366         0.448 0.243    0.2 uacr          30 Warning: Estimati…
 
# The remaining examples will all be limited to 10-year results  
 
# Example with SDI with valid zip code with SDI data available
estimate_risk(
  age = 66, 
  sex = "female",     
  sbp = 148, 
  bp_tx = FALSE,     
  total_c = 188,     
  hdl_c = 52,        
  statin = TRUE,    
  dm = TRUE,         
  smoking = TRUE,   
  egfr = 67,
  bmi = 30,
  zip = "59043",   # Lame Deer, MT (selected randomly)
  time = 10        # Note use of numeric 10 here (not "10yr")
)
#> Estimates are from: Base model adding SDI.
#> # A tibble: 1 × 8
#>   total_cvd ascvd heart_failure   chd stroke model over_years input_problems
#>       <dbl> <dbl>         <dbl> <dbl>  <dbl> <chr>      <int> <chr>         
#> 1     0.217 0.139         0.138  0.08  0.074 sdi           10 NA            

# Example with SDI with valid zip code without SDI data available
# (base model will be used)
estimate_risk(
  age = 66, 
  sex = "male",     
  sbp = 148, 
  bp_tx = FALSE,     
  total_c = 188,     
  hdl_c = 52,        
  statin = TRUE,    
  dm = TRUE,         
  smoking = TRUE,   
  egfr = 67,
  bmi = 30,
  zip = "00738",   # Fajardo, PR
  time = 10
)
#> Estimates are from: Base model.
#> # A tibble: 1 × 8
#>   total_cvd ascvd heart_failure   chd stroke model over_years input_problems
#>       <dbl> <dbl>         <dbl> <dbl>  <dbl> <chr>      <int> <chr>         
#> 1     0.224 0.142         0.138 0.083  0.072 base          10 NA            

# Example with full model (even though zip does not have available SDI, full 
# model used given availability of HbA1c and UACR; because zip is valid,
# column `input_problems` will be `NA`)
estimate_risk(
  age = 66, 
  sex = "female",     
  sbp = 148, 
  bp_tx = FALSE,     
  total_c = 188,     
  hdl_c = 52,        
  statin = TRUE,    
  dm = TRUE,         
  smoking = TRUE,   
  egfr = 67,
  bmi = 30,
  hba1c = 9,
  uacr = 75,
  zip = "00738",   
  time = "10yr"
)
#> Estimates are from: Base model adding HbA1c, SDI, and UACR (also referred to as the full model).
#> # A tibble: 1 × 8
#>   total_cvd ascvd heart_failure   chd stroke model over_years input_problems
#>       <dbl> <dbl>         <dbl> <dbl>  <dbl> <chr>      <int> <chr>         
#> 1     0.288 0.178         0.218 0.117  0.087 full          10 NA            

# Example with full model (zip has SDI data available, UACR is valid, but
# HbA1c is not; column `input_problems` will specify problem with `hba1c`,
# but full model will still run given availability of the other two optional
# predictor variables)
estimate_risk(
  age = 66, 
  sex = "male",     
  sbp = 148, 
  bp_tx = FALSE,     
  total_c = 188,     
  hdl_c = 52,        
  statin = TRUE,    
  dm = TRUE,         
  smoking = TRUE,   
  egfr = 67,
  bmi = 30,
  hba1c = 20,
  uacr = 75,
  zip = "59043",   
  time = "10yr"
)
#> Please check the following optional variables: 
#> `hba1c` entered as 20, but must be between 4.5 and 15 (so set to NULL)
#> Estimates are from: Base model adding HbA1c, SDI, and UACR (also referred to as the full model).
#> # A tibble: 1 × 8
#>   total_cvd ascvd heart_failure   chd stroke model over_years input_problems    
#>       <dbl> <dbl>         <dbl> <dbl>  <dbl> <chr>      <int> <chr>             
#> 1     0.235 0.147         0.153 0.087  0.072 full          10 `hba1c` entered a…

# Expect table of `NA`s due to invalid input for `age` and `sbp`, and column
# `input_problems` to contain explanations about problems with `age` and `sbp`
res <- estimate_risk(
  age = 8675309, 
  sex = "female",    
  sbp = 112358, 
  bp_tx = TRUE,      
  total_c = 200,     
  hdl_c = 45,        
  statin = FALSE,    
  dm = TRUE,         
  smoking = FALSE,   
  egfr = 90,
  bmi = 35,
  time = "10yr"     
)
#> Please check the following required variables: 
#> `age` entered as 8675309, but must be between 30 and 79
#> `sbp` entered as 112358, but must be between 90 and 180

res
#> # A tibble: 1 × 8
#>   total_cvd ascvd heart_failure   chd stroke model over_years input_problems    
#>       <dbl> <dbl>         <dbl> <dbl>  <dbl> <chr>      <int> <chr>             
#> 1        NA    NA            NA    NA     NA none          NA `age` entered as …

# Quiet version of the above example
res <- estimate_risk(
  age = 8675309, 
  sex = "female",    
  sbp = 112358, 
  bp_tx = TRUE,      
  total_c = 200,     
  hdl_c = 45,        
  statin = FALSE,    
  dm = TRUE,         
  smoking = FALSE,   
  egfr = 90,
  bmi = 35,
  time = "10yr",     
  quiet = TRUE       # Suppresses messages, but not column `input_problems`
)

res
#> # A tibble: 1 × 8
#>   total_cvd ascvd heart_failure   chd stroke model over_years input_problems    
#>       <dbl> <dbl>         <dbl> <dbl>  <dbl> <chr>      <int> <chr>             
#> 1        NA    NA            NA    NA     NA none          NA `age` entered as …

# Note `input_problems` column is semicolon-separated, but it is easy to
# print as separate lines with `gsub()` and `cat()`, e.g.:
cat(gsub("; ", "\n", res$input_problems))
#> `age` entered as 8675309, but must be between 30 and 79
#> `sbp` entered as 112358, but must be between 90 and 180
res$input_problems |> gsub(pattern = "; ", replacement = "\n", x = _) |> cat()
#> `age` entered as 8675309, but must be between 30 and 79
#> `sbp` entered as 112358, but must be between 90 and 180
# ... and could, of course, also do with the {magrittr} pipe `%>%` if desired