public function getPageStart()
    {
        $request = $this->getRequest();
        if ($this->pageStart === null) {
            if ($request
                && isset($request[$this->getPaginationGetVar()])
                && $request[$this->getPaginationGetVar()] > 0
            ) {
                $this->pageStart = (int)$request[$this->getPaginationGetVar()];
            } else {
                $this->pageStart = 0;
            }
        }

        return $this->pageStart;
    }