@automate-medical/gli2012/dist/util.js

Continuous prediction equations for spirometric indices

export function GLIFunction(coefficients, lookups, age, sex, height, ethnicity, measured) {
    const c = coefficients[sex];
    const AfrAm = ethnicity === "AfrAm" ? 1 : 0;
    const NEAsia = ethnicity === "NEAsia" ? 1 : 0;
    const SEAsia = ethnicity === "SEAsia" ? 1 : 0;
    const Other = ethnicity === "Other" ? 1 : 0;
    const Lspline = lookups[sex][findIndex(age)][0]; // @TODO implements lookup for 3-95 vs. second method
    const Mspline = lookups[sex][findIndex(age)][1];
    const Sspline = lookups[sex][findIndex(age)][2];
    const L = c['q0'] + c['q1'] * Math.log(age) + Lspline;
    const M = Math.exp(c['a0'] + c['a1'] * Math.log(height) + c['a2'] * Math.log(age) + c['a3'] * AfrAm + c['a4'] * NEAsia + c['a5'] * SEAsia + c['a6'] * Other + Mspline);
    const S = Math.exp(c['p0'] + c['p1'] * Math.log(age) + c['p2'] * AfrAm + c['p3'] * NEAsia + c['p4'] * SEAsia + c['p5'] * Other + Sspline);
    const LLN = Math.exp(Math.log(M) + Math.log(1 - 1.645 * L * S) / L);
    const percent = (measured / M) * 100;
    const zscore = (Math.pow((measured / M), L) - 1) / (L * S);
    return {
        L,
        M,
        S,
        LLN,
        percent,
        zscore
    };
}
// @TODO is there a way to avoid this duplication so the runtime has access?
export const sexes = ["Male", "Female"];
export const ethnicities = ["Caucasian", "AfrAm", "NEAsia", "SEAsia", "Other"];
export function findIndex(age) {
    if (age % 0.25 === 0) {
        // @TODO is there a way to prove that this is going to be a lookup-able value?
        // @ts-ignore
        return age;
    }
    else {
        // @TODO same thing
        // @ts-ignore 
        return age - (age % 0.25);
    }
}