MediaWiki:Gadget-calculator-patients-core.js

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/**
 * @author Chris Rishel
 */
( function() {
    // Units for age (37 weeks = birth)
    mw.calculators.addUnits( {
        wk: {
            definition: '0.01923 year',
            offset: -37
        },
        mo: {
            definition: '1 month'
        },
        yr: {
            definition: '1 year',
            aliases: [ 'yo' ]
        }
    } );

    // Units for weight
    // Body weight needs to be treated as a different fundamental unit type from mass (otherwise it would cancel out
    // doing stoichiometry calculations.
    // Gram-weight, which uses short SI prefixes (e.g. 1 kgwt = 1000 gwt)
    mw.calculators.addUnitsBases( {
        weight: {
            toString: function( units ) {
                return units.replace( 'wt', '' );
            }
        }
    } );

    mw.calculators.addUnits( {
        gwt: {
            baseName: 'weight',
            prefixes: 'short'
        },
        lbwt: {
            baseName: 'weight',
            definition: '453.59237 gwt'
        }
    } );

    mw.calculators.addVariables( {
        age: {
            name: 'Age',
            type: 'number',
            minValue: '20 wk',
            maxValue: '125 yr',
            maxLength: 3,
            units: [
                'yr',
                'mo',
                'wk'
            ]
        },
        gender: {
            name: 'Gender',
            type: 'string',
            options: [
                '',
                'F',
                'M'
            ]
        },
        height: {
            name: 'Height',
            type: 'number',
            minValue: '20 cm',
            maxValue: '300 cm',
            maxLength: 3,
            units: [
                'cm',
                'm',
                'in',
                'ft'
            ]
        },
        weight: {
            name: 'Weight',
            type: 'number',
            minValue: '200 gwt',
            maxValue: '750 kgwt',
            maxLength: 3,
            units: [
                'kgwt',
                'lbwt',
                'gwt'
            ]
        }
    } );

    /**
     * Very basic patient calculations which may be used by many modules
     */

    mw.calculators.addCalculations( {
        ibw: {
            name: 'Ideal body weight',
            abbreviation: 'IBW',
            data: {
                variables: {
                    required: [ 'height', 'gender' ]
                }
            },
            units: 'kgwt',
            link: 'https://en.wikipedia.org/wiki/Human_body_weight#Ideal_body_weight',
            description: 'Ideal body weight may only be applied to persons 152 cm (60 inches) or taller',
            formula: '<math>\\mathrm{IBW} = \\mathrm{weight_{base}} + 2.3 * (\\mathrm{height_{in}} - 60) \\\\ \\mathrm{weight_{base}} =\\left\\{\t\\begin{array}{ll}\t\t\\text{45.5 kg}  & \\mbox{if } \\text{female} \\\\\t\t\\text{50 kg} & \\mbox{if } \\text{male}\t\\end{array}\\right.</math>',
            references: [
                'Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650–655.'
            ],
            calculate: function( data ) {
                if( data.height.toNumber( 'cm' ) < 152 ) {
                    throw new Error( 'Ideal body weight may only be applied to persons 152 cm (60 inches) or taller' );
                }

                var baseWeight;

                if( data.gender === 'F' ) {
                    baseWeight = 45.5;
                } else if( data.gender === 'M' ) {
                    baseWeight = 50;
                } else {
                    throw new Error( 'Invalid gender "' + data.gender + '"' );
                }

                // baseWeight + 2.3 kg for every inch over 5 feet
                return baseWeight + 2.3 * ( data.height.toNumber( 'in' ) - 60 );
            }
        },
        lbw: {
            name: 'Lean body weight',
            abbreviation: 'LBW',
            data: {
                variables: {
                    required: [ 'gender', 'height', 'weight' ]
                }
            },
            units: 'kgwt',
            link: 'https://en.wikipedia.org/wiki/Lean_body_mass',
            formula: '<math>\\mathrm{LBW} = \\begin{cases} \\frac{9270 * \\mathrm{weight_{kg}}}{8780+(244*\\mathrm{BMI}))} & \\mbox{if } \\text{female} \\\\\\\\ \\frac{9270 * \\mathrm{weight_{kg}}}{6680+(216*\\mathrm{BMI}))} & \\mbox{if } \\text{male} \\end{cases}</math>',
            references: [
                'Janmahasatian S, Duffull SB, Ash S, Ward LC, Byrne NM, Green B. Quantification of lean bodyweight. Clin Pharmacokinet. 2005; 44(10): 1051-65.'
            ],
            calculate: function( data ) {
                if( data.gender === 'F' ) {
                    return 9270 * data.weight.toNumber( 'kgwt' ) / ( 8780 + 244 * data.weight.toNumber( 'kgwt' ) / Math.pow( data.height.toNumber( 'm' ), 2 ) );
                } else if( data.gender === 'M' ) {
                    return 9270 * data.weight.toNumber( 'kgwt' ) / ( 6680 + 216 * data.weight.toNumber( 'kgwt' ) / Math.pow( data.height.toNumber( 'm' ), 2 ) );
                } else {
                    throw new Error( 'Invalid gender "' + data.gender + '"' );
                }
            }
        },
        tbw: {
            name: 'Total body weight',
                abbreviation: 'TBW',
                data: {
                variables: {
                    required: [ 'weight' ]
                }
            },
            units: 'kgwt',
            calculate: function( data ) {
                return data.weight.toNumber( 'kgwt' );
            }
        }
    } );
}() );