The National Labor Relations Board has substantially reduced its record backlog of cases, but workers, unions and employers still face lengthy delays in having disputes resolved, especially in the health care industry, a House subcommittee was told yesterday.

"I believe that the board is in relatively good shape and should soon be getting better," NLRB Chairman Donald L. Dotson said.

Last month's Senate confirmation of new members Wilford Johansen and Marshall Babson will raise the board to its full complement of five members for the first time in 22 months and will help cut its backlog further, Dotson said.

But critics from the American Nurses Association and the United Food and Commercial Workers said the board has failed to end the delays of up to five years for nurses who voted to unionize but whose employers have delayed or avoided recognizing the union.

The NLRB, which adjudicates charges of unfair labor practices and supervises union elections, has been strongly criticized by organized labor for delays in hearing claims by employes alleging illegal dismissal for union activities and by unions alleging that employers are refusing to recognize or bargain with them.

The NLRB's backlog hit 1,647 cases in February 1984, a record for its 50-year history, but has declined to 1,236 as of June 1, according to board data.

Rosemary M. Collyer, the NLRB's general counsel, said the backlog fell because layoffs and plant-closings in heavily unionized industries reduced the number of new cases and because unions were heavily involved in 1984 political campaigns and spent less time on organizing, which generates many NLRB cases. Dotson said the board is also using a "speed team" to handle cases as quickly as possible.

Rep. Barney Frank (D-Mass.), chairman of the manpower and housing subcommittee of the Government Operations Committee, commended the board for its 25 percent backlog reduction but said "working men and women continue to be denied their rights . . . and the government continues to fail to deliver on its promise" in overseeing labor relations.

Pamela A. Ames, director of labor relations for the 185,000-member American Nurses Association, cited five cases of hospital nurses winning NLRB-supervised union representation votes as long ago as 1980 but still waiting for the board to order hospital management to negotiate with the union.

Hospitals are able to delay cases because the board has not issued clear rulings on whether registered nurses can be a "bargaining unit" on their own or most include other professionals in their vote to unionize. Dotson said the board may consider issuing rules to clarify such cases.