README

PHP implementation of the Expanded Disability Status Scale (EDSS) calculator, based on the scoring table by Ludwig Kappos, MD (University Hospital Basel) and the Neurostatus-EDSS™ standard (Kurtzke, 1983).

This library calculates the EDSS score from 7 Functional System (FS) scores and an Ambulation score, used in the clinical assessment of Multiple Sclerosis.

Based on the JavaScript reference implementation (forked from adobrasinovic/edss).

Installation

composer require atiweb/edss-in-php

Usage

Direct calculation with individual scores

Parameter names match the JS reference: calculateEDSS(visualFunctionsScore, brainstemFunctionsScore, pyramidalFunctionsScore, cerebellarFunctionsScore, sensoryFunctionsScore, bowelAndBladderFunctionsScore, cerebralFunctionsScore, ambulationScore)

use Atiweb\Edss\EdssCalculator;

$calculator = new EdssCalculator();

$edss = $calculator->calculate(
    visualFunctionsScore: 1,          // Visual (Optic) — raw 0-6
    brainstemFunctionsScore: 2,       // Brainstem — 0-5
    pyramidalFunctionsScore: 1,       // Pyramidal — 0-6
    cerebellarFunctionsScore: 3,      // Cerebellar — 0-5
    sensoryFunctionsScore: 1,         // Sensory — 0-6
    bowelAndBladderFunctionsScore: 4, // Bowel & Bladder — raw 0-6
    cerebralFunctionsScore: 2,        // Cerebral (Mental) — 0-5
    ambulationScore: 1,               // Ambulation — 0-16
);

echo $edss; // "4"

From an associative array

By default, calculateFromArray() expects English field names:

$data = [
    'visual_functions_score' => '1',
    'brainstem_functions_score' => '2',
    'pyramidal_functions_score' => '1',
    'cerebellar_functions_score' => '3',
    'sensory_functions_score' => '1',
    'bowel_and_bladder_functions_score' => '4',
    'cerebral_functions_score' => '2',
    'ambulation_score' => '1',
];

$edss = $calculator->calculateFromArray($data);
echo $edss; // "4"

With REDCap Portuguese field names

If your data uses the Portuguese field names from REDCap/REDONE.br, pass the built-in FIELDS_REDCAP_PT mapping:

$redcapData = [
    'edss_func_visuais' => '1',                       // Visual Functions Score
    'edss_cap_func_tronco_cereb' => '2',              // Brainstem Functions Score
    'edss_cap_func_pirad' => '1',                     // Pyramidal Functions Score
    'edss_cap_func_cereb' => '3',                     // Cerebellar Functions Score
    'edss_cap_func_sensitivas' => '1',                // Sensory Functions Score
    'edss_func_vesicais_e_instestinais' => '4',       // Bowel & Bladder Functions Score
    'edss_func_cerebrais' => '2',                     // Cerebral Functions Score
    'edss_func_demabulacao_incapacidade' => '1',      // Ambulation Score
];

$edss = $calculator->calculateFromArray($redcapData, EdssCalculator::FIELDS_REDCAP_PT);
echo $edss; // "4"

// Longitudinal data with suffix
$edss = $calculator->calculateFromArray($longitudinalData, EdssCalculator::FIELDS_REDCAP_PT, '_long');

Custom field mapping

You can define your own field name mapping for any data source:

$myFields = [
    'visual'       => 'my_visual_field',
    'brainstem'    => 'my_brainstem_field',
    'pyramidal'    => 'my_pyramidal_field',
    'cerebellar'   => 'my_cerebellar_field',
    'sensory'      => 'my_sensory_field',
    'bowelBladder' => 'my_bowel_bladder_field',
    'cerebral'     => 'my_cerebral_field',
    'ambulation'   => 'my_ambulation_field',
];

$edss = $calculator->calculateFromArray($myData, $myFields);

Score conversions

The Visual and Bowel & Bladder Functional Systems use a wider raw scale that is compressed for EDSS calculation:

// Visual: raw 0-6 → converted 0-4
//   0→0, 1→1, 2-3→2, 4-5→3, 6→4
EdssCalculator::convertVisualScore(3);  // 2
EdssCalculator::convertVisualScore(5);  // 3

// Bowel & Bladder: raw 0-6 → converted 0-5
//   0→0, 1→1, 2→2, 3-4→3, 5→4, 6→5
EdssCalculator::convertBowelAndBladderScore(4);  // 3
EdssCalculator::convertBowelAndBladderScore(6);  // 5

Functional Systems

Note: The Ambulation score (≥3) directly determines the EDSS score (≥5.0). When Ambulation is 0-2, the EDSS is determined by the combination of FS scores.

Algorithm

The EDSS calculation follows a two-phase approach:

Phase 1: Ambulation-driven (EDSS ≥ 5.0)

When the Ambulation score is ≥ 3, it directly maps to an EDSS value:

Phase 2: FS-driven (EDSS 0 – 5.0)

When Ambulation is 0-2, the EDSS is calculated from the combination of the 7 FS scores based on the Kappos scoring table, considering:

• The maximum FS score and how many systems have that score
• The second-highest FS score and its frequency
• The Ambulation score (0, 1, or 2)

Field Name Mappings

The library includes built-in constants for field name mappings:

You can also pass your own array<string, string> mapping to calculateFromArray().

Other implementations

Testing

composer install
composer test

The test suite includes 70+ test cases covering:

• All EDSS ranges from 0 to 10
• Visual and Bowel/Bladder score conversions
• All ambulation-driven scores
• Edge cases for FS combinations
• The reference example from the JavaScript implementation
• Custom field mapping support

References

• Kurtzke JF. Rating neurologic impairment in multiple sclerosis: an expanded disability status scale (EDSS). Neurology. 1983;33(11):1444-1452.
• Neurostatus-EDSS™
• JavaScript reference implementation

License

MIT