The strike against the Group Health Association entered its 12th day yesterday, with negotiations between striking nurses and GHA at a standstill and representatives of the nurses' union scheduled to meet last night with the association's board of trustees.

"The board has been misinformed," said Denise Mullane, president of the Registered Nurses and Physical Therapists Association, which represents the 85 persons who walked off the job 13 days ago.

Martin Krall, attorney for GHA, said that the nurses asked for the meeting to "try to convince the board that their demands are fair and equitable." However, Krall said, "rest assured that the board has been kept informed."

Last Saturday, he said, the nurses offered a new wage and staffing proposal to GHA, which he termed "not a substantial change . . . though I wouldn't say there was no change at all." GHA has not yet offered a counterproposal.

Krall said he did not expect any dramatic results from last night's meeting. Noting that the board comprises GHA member-patients and that any salary increase granted the nurses would be passed on, Krall said GHA members typically "don't represent the wealthiest sector of the community."

The strike began April 1, when negotiations broke down over salaries and staffing. GHA's five metropolitan-area centers have remained open, with routine services being delayed. Emergency services have not been disrupted.