In an interview with Mexican newspaper Milenio Semanal earlier this month, Salvador Navarrete said hopes for the president's recovery were very slim and the leader had less than two years to live.
There has been much controversy around Chavez's caner, but the 57-year-old Venezuelan leader maintains his health is gradually improving after three to four courses of chemotherapy in Cuba.
In his interview, Navarrete, who had been caring for Chavez from 2002 until recently, quoted "sources" as saying that Chavez's health was very poor and that his treatment had not yielded significant results.
Soon after the interview, police searched Navarrete's office, prompting him to flee the country to avoid further tensions with the authorities, media report said.
In June, Chavez underwent two operations in Havana: first for a pelvic abscess and later to remove a cancerous tumour.
Earlier this month, Chavez wrote on his Twitter account: "I'm free of disease. However, every four months I will have to be monitored to verify the ... good evolution of what was a disease and what we're continuing to treat."
In late September, Roger Noriega, a former US assistant secretary of state for Western Hemisphere affairs, accused the Venezuelan authorities of hiding the truth about Chavez's health ahead of presidential elections due in October 2012.