$output = fopen("php://output",'w') or die("Can't open php://output");
header("Content-Type:application/csv");
header("Content-Disposition:attachment;filename=auditresults_$i.csv");
fputcsv($output, array('id','createdon','colum1','column2','column3','colum4'));
foreach ($items as $item) {
     fputcsv($output, $item)
}
fclose($output) or die("Can't close php://output");