I was taught at school that in UK English you must use "as" when what follows is a clause. Like your example.
As I said, you have to study harder to pass your exam.
BUT, in US they use "like".
As I pointed out, you have to study harder to pass your exam.
From OED >> point out: [REPORTING VERB] say something to make someone aware of a fact or circumstance: [with CLAUSE] she pointed out that his van had been in the car park all day | [with DIRECT SPEECH] ‘Most of the people round here are very poor,’ I pointed out.
From OED >>> state: 1*[REPORTING VERB] express something definitely or clearly in speech or writing: [with CLAUSE] the report stated that more than 51 per cent of voters failed to participate | [with DIRECT SPEECH] ‘Money hasn't changed me,’ she stated firmly | [with OBJ.] people will be invited to state their views.