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PREDICTORS OF INTERVENTION SUCCESS AND FAILURE IN A PREVENTIVE HOME VISITING PROGRAM

Jon Korfmacher

Prevention Research Center for Family and Child Health, UCHSC Department of Pediatrics 303 E. Seventeenth Av, #200 Denver CO 80203

Preventive intervention research has targeted its focus mostly on outcome evaluation, determining if an intervention is effective across an entire group of participants. Recent investigations, however, have focused increased attention on the process by which services are delivered, and in the differential effectiveness of the intervention on different groups of individuals. An important, although relatively unexamined, aspect of program process research is the examination of intervention “failures”, those participants who do not improve in response to treatment, or who may in fact have worse outcomes over time. Understanding and identifying these cases provides information to programs that may allow them to provide more appropriate and effective services in the future. This presentation reports a preliminary examination of differences between families who show positive change and those who show a decline in functioning in a home visiting intervention for first-time mothers and their infants.

Subjects come from a sample of 228 first-time mothers and their infants who received home visitation by a public health nurse as part of a randomized trial conducted in Memphis, TN. Mothers were predominantly African-American, poor, young, and unmarried. The intervention began during pregnancy and lasted until the child was two. Nurses visited approximately every other week and focused on maternal and child physical health, caregiving, and mother’s own life-course development. Previous reports have shown intervention effectiveness in improving caregiving, maternal health during pregnancy, mother’s feelings of psychological mastery, and reducing the number of subsequent pregnancies.

Because many of these variables were assessed at multiple time points, it is possible to identify subjects who showed improvement or decline in their functioning over the course of the intervention. Variables selected for this investigation, all of which showed positive intervention effects for the sample as a whole, include home caregiving environment, empathic attitudes towards children, feelings of psychological mastery, and child behavior towards mother during standardized assessment of parent- child interaction.

Subjects were identified as having improved if they showed positive change (with at least 314 of a standard deviation difference) from the earliest assessment point (intake for mastery and parent attitudes; six months for child behavior; 12 months for home environment) to the outcome assessment at 24 months (sample size range from to 43 to 70). Subjects were identified as having declined if they showed negative change (with at least 3/4 of a standard deviation difference) between these same assessment points (sample size range from 22 to 41). These groups were then contrasted on measures of treatment process (total length of contact with nurse home visitor, emotional engagement during sessions, and perception of empathy from nurse home visitor), as well individual characteristics measured at intake (maternal age, education) or the child’s birth (infant birthweight).

Preliminary results suggest that families who showed a decline in functioning, compared to those who showed improvement, had less emotional engagement with the intervention and had less contact with and perceived less empathy from their nurse home visitor. Sociodemographic characteristics do not predict differences between the two groups, although additional analyses to be completed will examine personal characteristics of mothers measured at intake, such as mental health status and childrearing history. Issues raised in interpreting and discussing results include considering the direction of effects and how to use these findings in improve program services.