Maternally administered interventions for preterm infants in the NICU: effects on maternal psychological distress and mother-infant relationship.

Although studies have examined the effects of interventions focused on preterm infants, few studies have examined the effects on maternal distress (anxiety, depressive symptoms, post-traumatic stress symptoms, parenting stress) or parenting. This study examined the effects of the auditory-tactile-visual-vestibular (ATVV) intervention and kangaroo care (KC) on maternal distress and the mother-infant relationship compared to an attention control group. 240 mothers from four hospitals were randomly assigned to the three groups. Maternal characteristics in the three groups were similar: 64.1% of ATVV mothers, 64.2% of KC mothers, and 76.5% of control mothers were African American; maternal age averaged 26.3 years for ATVV mothers, 28.1 for KC mothers, and 26.6 for control mothers; and years of education averaged 13.6 for ATVV and KC mothers, and 13.1 for control mothers. Mothers only differed on parity: 68.4% of ATVV and 54.7% of KC mothers were first-time mothers as compared to 43.6% of control mothers. Their infants had a similar mean gestational ages (27.0 weeks for ATVV, 27.2 for KC, and 27.4 for control) and mean birthweights (993 g for ATVV, 1022 for KC, and 1023 for control). Mothers completed questionnaires during hospitalization, and at 2, 6 and 12 months corrected age on demographic characteristics, depressive symptoms, state anxiety, post-traumatic stress symptoms, parenting stress, worry about child health, and child vulnerability (only at 12 months). At 2 and 6 months, 45-min videotapes of mother-infant interactions were made, and the HOME Inventory was scored. Behaviors coded from the videotapes and a HOME subscale were combined into five interactive dimensions: maternal positive involvement and developmental stimulation and child social behaviors, developmental maturity, and irritability. Intervention effects were examined using general linear mixed models controlling for parity and recruitment site. The groups did not differ on any maternal distress variable. Kangaroo care mothers showed a more rapid decline in worry than the other mothers. The only interactive dimensions that differed between the groups were child social behaviors and developmental maturity, which were both higher for kangaroo care infants. Change over time in several individual infant behaviors was affected by the interventions. When mothers reported on the interventions they performed, regardless of group assignment, massage (any form including ATVV) was associated with a more rapid decline in depressive symptoms and higher HOME scores. Performing either intervention was associated with lower parenting stress. These findings suggest that as short-term interventions, KC and ATVV have important effects on mothers and their preterm infants, especially in the first half of the first year.

The promise of the state space approach to time series analysis for nursing research.

BACKGROUND: Nursing research, particularly related to physiological development, often depends on the collection of time series data. The state space approach to time series analysis has great potential to answer exploratory questions relevant to physiological development but has not been used extensively in nursing. OBJECTIVES: The aim of the study was to introduce the state space approach to time series analysis and demonstrate potential applicability to neonatal monitoring and physiology. METHODS: We present a set of univariate state space models; each one describing a process that generates a variable of interest over time. Each model is presented algebraically and a realization of the process is presented graphically from simulated data. This is followed by a discussion of how the model has been or may be used in two nursing projects on neonatal physiological development. RESULTS: The defining feature of the state space approach is the decomposition of the series into components that are functions of time; specifically, slowly varying level, faster varying periodic, and irregular components. State space models potentially simulate developmental processes where a phenomenon emerges and disappears before stabilizing, where the periodic component may become more regular with time, or where the developmental trajectory of a phenomenon is irregular. DISCUSSION: The ultimate contribution of this approach to nursing science will require close collaboration and cross-disciplinary education between nurses and statisticians.

Advances in mediation analysis can facilitate nursing research.

BACKGROUND: Two recent advances in the statistical methods for testing hypotheses about mediation effects are important for nursing science. First, bootstrap sampling distributions provide more accurate tests of hypotheses about mediated effects. Second, methods for testing statistical hypotheses about subgroup differences in mediation models (moderated mediation) are now well developed. OBJECTIVE: The aims of this study were to demonstrate the use and relatively simple computation of bootstrap sampling distributions in tests of mediation effects and to demonstrate a recently refined method for testing hypotheses about moderated mediation. METHOD: Using hypothetical data, a step-by-step demonstration was provided of the construction of a bootstrap sampling distribution for a correlation coefficient. Then, tests of mediation and moderated mediation were demonstrated using data from a clinical trial of an intervention for caregivers of patients with Parkinson's disease or Alzheimer's disease. In a model hypothesizing that mutuality between caregiver and care recipient mediates the effect of objective on subjective levels of caregiver burden, the bootstrap sampling distribution was calculated of the mediation effect and, from that, two types of 95% confidence intervals for it. Then the hypothesis was tested that the mediating effect of mutuality was stronger for caregivers of patients with Parkinson's disease than for caregivers of patients with Alzheimer's disease. CONCLUSIONS: Statistical hypothesis testing should never dictate all conclusions. However, the statistical advances in mediation analysis described here will facilitate nursing research as both nurse scientists and methodologists understand their assumptions and logic.