$sub = db_select('comment', 'c');
$sub->addField('c', 'cid');
$sub->condition('c.uid', 1);
$sub = $sub->countQuery();
$sub->preExecute();

$select = db_select('node', 'n');
$select->addField('n', 'nid');
$select->condition($sub, '0', '<');

$select->execute();

dsm((string) $select);

####################

SELECT n.nid AS nid
FROM 
{node} n
WHERE (SELECT COUNT(*) AS expression
FROM 
(SELECT 1 AS expression
FROM 
{comment} c
WHERE  (c.uid = :db_condition_placeholder_0) ) subquery)