Subject Retention, Measurement and Outcomes in Longitudinal Investigations:

1. Subject Retention, Measurement and Outcomes in Longitudinal Investigations: Examples from a Study of Prenatal Cocaine Exposure September 30, 2010 Presented by Sonia Minnes, Ph.D., Assistant Professor of Social Work, Mandel School of Applied Social Sciences 96 Years of Leadership in Social Justice

2. Longitudinal Design Defined “Longitudinal” describes a wide variety of research methods. The “one sine qua non of longitudinal research is that the entity under investigation is observed repeatedly as it exists and evolves over time”. Baltes and Nesselroade (1979) % Women with clinically elevated Psychological Distress by Cocaine Group

3. Longitudinal Research Assess same participant across time waves –Panel Study Sample from the same population over time Experimental, quasi-experimental, and non-experimental

4. Longitudinal Research Answers questions about persistence, change, growth or developmental process Can detect “sleeper” effects that occur in later development Examination of divergence of groups Relationship of early difficulties and later outcomes Rates of change Allows for use of time varying covariates in analyses

5. Potential Problems Very high cost, particularly with initial evaluation Can not provide answers to pressing questions Complexity of design and interpretation Threats to internal and external validity ◊ Measurement issues ◊ Subject Attrition

6. Project Newborn - Next Steps Funded by the National Institute on Drug Abuse (R01 07957) Prospective, non-experimental, birth cohort design

7. Project Staff Adelaide Lang, Ph.D. Psychologist/Project Coordinator Paul Weishampel, M.A. Psychometrician Diana Fox, B.A. Research Assistant Laurie Ellison, M.S.S.A Social Worker Meeyoung Oh Min, Ph.D. Research Assistant Professor Miaoping Wu M.S. Biostatistician, Data Manager Jeff Albert, Ph.D. Biostatistician

8. Project Newborn Participants Women and infant dyads Low socio-economic status (receiving Medicaid) Maternity Ward at MetroHealth Medical Center (Children born September 1994-July 1996) Women Screened for substance use at the time of delivery due to: ◊ Lack of prenatal care ◊ Behavior suggesting intoxication ◊ History of DHS involvement ◊ Self-admitted drug use

9. Exclusion Criteria Maternal age <19 Maternal chronic psychiatric or medical illness including HIV Low maternal IQ Identified fetal alcohol syndrome Non-English Speaking

10. Definition of Fetal Cocaine Exposure Cocaine group (n=218) • Self report of cocaine use • Meconium screen positive for cocaine metabolite • Maternal or infant urine positive for cocaine metabolite Control group (n=197) • Negative on all measures

11. Project Newborn Assessment Points Phase I (1994-1998) Birth – 6 months – 12 months – 24 months Phase II (1998-2003) 4 years – 6 years Phase III (2003-2009) 9 years – 10 years – 11 years – 12 years Phase IV (2009-2014) 15 years – 17 years (substance use assessment every 6 months)

12. Assessment Domains Child Medical birth outcomes Growth CNS Neurobehavioral Attention & Memory Cognitive Language Behavior Risk Taking Witness/Victim violence Mental Health (substance use) Fine and Gross Motor

13. Assessment Domains Maternal/Environmental Pregnancy outcome Health Psychopathology Parenting Stress Coping Social Support Cognitive/Verbal ability SES Ongoing Drug Use Partner violence

14. Time Varying Covariates Caregiver Placement ◊ Foster or Adoptive Care ◊ Biologic Relatives ◊ Biologic Mother Quality of Home Environment Caregiver Psychological Distress Caregiver Drug Use

15. Importance of Retention Rates Maintains characteristics of original sample Retention reduces threats to external validity High attrition can nullify benefits of intervention research, reduce statistical power High attrition is common in at risk transient populations (mentally ill, homeless)

16. Estimating Sample Size for Longitudinal Studies Study Design Compute number of subject needed for adequate power to detect effects Use liberal estimates of subject loss over time Over recruit number of subjects depending on nature of research question

17. Methods to Minimize Attrition Recruit a cohesive staff Provide ongoing education on importance of retention Value every subject, every encounter Keep excellent records Budget for stipends and retention expenses Check retention progress regularly Be flexible, ingenious, adaptable Get professional help when indicated Regular, frequent contacts

18. Retention Rates from Project * The recruited group consisted of 218 cocaine exposed and 197 non-cocaine exposed children. From birth to 2 years, there were 11 deaths, 8 in cocaine-positive children and 3 in cocaine-negative children.

19. Project Newborn - Examples Meaningful personal contacts Keeps records of all contacts Over sight of all recruitment and retention activities ◊ Training for subject contacts ◊ Budgeting and timing of cards and gifts ◊ Reporting bimonthly percentage of subject seen/expected visits ◊ Adaptability Persistence • Laurie Ellison – MSSA, LISW

20. Project Newborn Bimonthly staff meetings Report on recruitment and visits completed Regular analyses of attrition of systematic loss of subjects Collection of multiple other contacts (updated regularly) ◊ Get consent to contact others who know whereabouts ◊ Update info regularly (provide incentives for updates) ◊ Coach subject on the importance of keeping us informed ◊ Communication via letter, phone, through a relative, text, email, newsletter

21. Staff Cohesiveness

22. Project Newborn Small gifts Donated baby blankets (given at early visits) Regular birthday gift and cards Copies of Video Tapes used for Research Grocery certificate at the holidays Stipends in cash ($35, $50, $100, $175)

23. Project Newborn Value every subject Small gift for child to take home Cab rides, lunch for both mom and child, coffee, snacks

24. Project Newborn Value every subject Accommodate subjects who have moved out of town ◊ Hire a local psychologist to give basic assessments ◊ Provide resources to family for travel

25. Go Where Participants Are

26. Measurement Issues Repeated measures can produce testing effect Sensitization Practice Solution Space subject contacts far enough apart Provide specific instruction to answer questions without regard for previous answers Use alternative forms of instrument

27. Measurement Issues Measures need to be sensitive to change within individuals Changes in the meaning of measures across time Measuring the same construct over the developmental course (birth -17 years) with different measures Choice of test measure difficult in early stages of human development when abilities change rapidly)

28. Examples from Project Newborn Measurement of Cognitive Development Infancy Research – lack of predictive relationship between infant measures of cognitive development to later intellectual outcome

29. Project Newborn – Early Cognitive Outcomes Singer, LT, Arendt, R, Minnes, S, Farkas, K, Salvator, a, Kirchner, HL and Kliegman, R.(2002). Cognitive and motor outcomes of cocaine-exposed infants. Journal of the American Medical Association, 287(15), 1952-1960. Dependent Measure Bayley Scales of Infant Development - Cognitive and Motor Development ◊ Age standardized norms ( average =100, standard deviation=15) ◊ Not predictive of later IQ until 18-24 months ◊ Good at measuring group or population effects ◊ Test differs at every age ◊ Examiner bias, skill, and child temperament make it a difficult test to administer reliably

30. Project Newborn – Early Cognitive Outcomes * Means adjusted for Caregiver Wechsler Adult Intelligence Scale-Revised, block design score of the current caregiver at birth and for biological maternal parity and educational level. Mental Development Index* Age

31. Examples from Project Newborn Lewis, B, Kirchner, L., Short, EJ, Weishampel, P,Satayathum, S, and Singer, L.T. (2007). Prenatal Cocaine and Tobacco Effects on Children’s Language Trajectories, Pediatrics, 120, e78-e85. Expressive, Receptive and Total Language Assessed Dependent Measure ◊ Preschool Language Scale (PLS) (1 and 2 years corrected) ◊ Clinical Evaluation of Language Fundamentals- Preschool (CELF) (4 years) ◊ Comprehensive Assessment of Spoken Language (CASL) (6years)

32. Language Outcomes Statistical Analyses Standard scores for expressive, receptive and total scores Each measurement was internally standardized to create z scores at each visit using all available child data Analyses of z scores using random coefficient models Actual age of the child used to capture trends over time better Changing effects over time assessed – not significant Examination of main effects for cocaine

33. Total Language z Score by Age Prenatally cocaine exposed children had a mean standardized total language score of 0.18 SD lower than non cocaine exposed children at all time points.

34. Mean Language Scores by Age Receptive Expressive Total Y Y Y X X X X - Age Y - Language Outcome Score, Mean

35. Project Newborn Longitudinal Outcomes Sonia Minnes, Lynn T. Singer , H. Lester Kirchner , Elizabeth Short , Barbara Lewis, Sudtida Satayathum, Dyianweh Queh (2010). The effects of prenatal cocaine exposure on problem behavior in children 4–10 years. Neurotoxicology and Teratology, 32(4) 443-451. Dependent Measure ◊ Child Behavior Checklist 4-18 (Caregiver Report) ◊ Administered at (4, 6, 9 and 10 years)

36. Delinquency by Age, Cocaine Status & Gender Figure demonstrates that cocaine effect on problem delinquent behavior overall but that increased clinical level diverge at 9 years. % above clinical cutoff for delinquency

37. Project Newborn – What’s Next? Substance use assessments at 9, 10, 11 and 12 years Substance use assessment resumed at 15 years Accompanying biologic assessments (hair, urine, blood) Will continue every 6 months until 18 years Survival analyses/event history analyses Risks of early substance use Identification of predictors of problem substance use Relationship to prenatal drug exposures