Backbone.js fetch with parameters

Following the documentation, I did:

var collection = new Backbone.Collection.extend({
        model: ItemModel,
        url: '/Items'
})

collection.fetch({ data: { page: 1} });

the url turned out to be: http://localhost:1273/Items?[object%20Object]

I was expecting something like http://localhost:1273/Items?page=1

So how do I pass params in the fetch method?