THE Russian parliament launched a debate on the next steps for reform yesterday without the presence of President Boris Yeltsin.Mr. Yeltsin had been scheduled to address the opening parliamentary session, but was advised by doctors to take the day off, according to Acting Speaker Ruslan Khasbulatov, who assured deputies there were no serious health problems. In his opening remarks, Mr. Khasbulatov focused on the need to preserve the unity forged among reform-minded legislators while defending the parliament building during the Aug. 19-21 coup attempt. "We can't think the danger [to reform] is past," he said. "The environment that could give rise to a successful conspiracy still remains." Some Russian parliament deputies suggested that a healthy Yeltsin was needed to expedite reforms and head off any potential upheaval sparked by widely expected shortages of food and heating this winter. The coup's collapse last month established Yeltsin as the Soviet Union's most influential politician and leader of the market-style reform movement. But other deputies said Yeltsin's illness would not threaten the reform process, even if he were unable to perform duties for a long time. "He has assembled around him a very talented group of men, who are more than capable of carrying on his ideas," said Deputy Nikolai Vorontsov. This session is expected to debate measures to improve social conditions and the food supply, a new local election law, and Russia's representation in the revamped Soviet parliament. With Yeltsin disabled, however, the power struggle between the legislative and executive branches of government could slow reform plans. Many deputies pointed to a recent decree making the government subordinate to Yeltsin as evidence of an imperial presidency in the making. The move essentially left former Russian Prime Minister Ivan Silayev without any power. Mr. Silayev resigned from the post Wednesday to concentrate his energies as chairman of the inter-republican economic commission, the newly formed structure in charge of coordinating economic activity in the new Soviet Union.