A NEW STUDY of abused children treated at Children's Hospital has found a striking increase in the number who have been repeatedly abused and neglected, in some cases fatally. The reasons for that disturbing finding aren't clear. The need for better protection for abused children--nationally as well as locally--is clear.

While the study finds that incidents of repeated abuse more than doubled during 1981 and the first half of 1982, the hospital's repetition rate still remained far below the estimated national rate of 13 percent. Children's Hospital, however, is only one of several agencies and hospitals treating child abuse, and its prevention efforts--financed entirely by the hospital's own resources--are more advanced than those of many other involved agencies. For this reason the sharp increase in repeated abuse cases at Children's is even more a cause for concern.

One explanation offered for the increase is the depth and duration of the economic downturn. Hard times increase family tensions, and many areas have reported that child abuse has risen along with unemployment over the last few years. But the study's author, Mary L. Holman, is concerned that the District's new child welfare policy may also be a contributing factor. That policy stresses returning abused and neglected children to their homes whenever possible rather than transferring them to other care.

The connection between city policies and the treatment of abused children is not, however, as direct as you might suppose. Most children who enter the city's child welfare system have not been physically or sexually abused. Typically they arrive in the city's care as the result of general neglect or because their parents have health, housing or employment problems. Trying to shore up these families so that they can care for their own children is certainly better than setting the children adrift in the city's previously ill-supervised foster care system.

Conversely, most of the area's abused children never enter the child welfare system. Children's Hospital and other voluntary agencies can offer counseling and other help to parents, but unless the police--and subsequently the courts--decide that the child needs further protection, the hospital must rely on voluntary cooperation by parents who are frequently angered or embarrassed by the intervention. Since it may be difficult for caseworkers to establish parental responsibility for sexual or physical abuse to the satisfaction of the authorities, some children don't receive the protection they need.

No system for dealing with the emotional issue of child abuse can be foolproof. And progress in coordinating the efforts of the various agencies involved-- under the aegis of annteragency committee recently reactivated by Mayor Barry--is continuing. Still, it is not hard to conclude that a system that allows small children to be returned to abusive parents who are psychotic, homicidal or addicted--as the study found --is intolerable and must be fixed now.