The midfielder returned to Upton Park from Liverpool in January, but a hamstring problem has troubled him for a large part of the current campaign.
His current deal is due to expire in the summer, but Allardyce has insisted that he would only consider offering the former England international fresh terms if he can remain fit.
"It's not about proving his fitness, it's about staying fit. There is a big difference. Joe is fit. Even in his 30s his fitness stats are very good," said the boss. "Joe's concern is not picking up injuries. A proven period of time when the injuries do not reoccur is more what we are trying to look for and evaluate.
"At the end of the season we evaluate what the contribution of the players is - not just what he has done in the games he has played, but also how many games he has played.
"If he has only played five and you divide that over his wages, it's pretty expensive. That is a really good equation to work by when you talk about new contracts."
Cole has scored three goals in 18 outings since he rejoined the Hammers.