public function getRelationsFor($respondentId, $patientNr = null, $organizationId = null, $onlyActive = true)
    {
        static $relationsCache = array();

        if (is_null($respondentId)) {
            $respondentId = $this->loader->getUtil()->getDbLookup()->getRespondentId($patientNr, $organizationId);
        }

        if (!array_key_exists($respondentId, $relationsCache)) {
            $relations = array();
            $filter = array('grr_id_respondent'=>$respondentId);
            if ($onlyActive) {
                $filter['grr_active'] = 1;
            }
            $rawRelations = $this->load($filter);
            foreach ($rawRelations as $relation)
            {
                $relations[$relation['grr_id']] = join(' ', array($relation['grr_type'], $relation['grr_first_name'], $relation['grr_last_name']));
            }
            $relationsCache[$respondentId] = $relations;
        }

        return $relationsCache[$respondentId];
    }