function getColumnName($response, $title)
    {
        $fieldmap = createFieldMap($response->survey, 'full', null, false, $response->attributes['startlanguage']);
 
        foreach ($response->attributes as $key => $value) {
            if (array_key_exists($key, $fieldmap)) {
                if (array_key_exists('title', $fieldmap[$key]) && $fieldmap[$key]['title'] === $title) {
                    return $key;
                }
            }
        }
 
        return false;
    }

Yii::import('application.helpers.common_helper', true);
$response = SurveyDynamic::model(123456)->findByPk(1);
var_dump(getColumnName($response, 'completed')); // outputs '454344X20X386'