Prevention of Attrition Keys to Successful Cohort Maintenance Patricia B. Crawford, DrPH, RD Adjunct Professor Co-Director, Center for Weight and Health.

Prevention of AttritionKeys to Successful Cohort Maintenance

Patricia B. Crawford, DrPH, RDAdjunct Professor

Co-Director, Center for Weight and Health

University of California, Berkeley

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Mission

Provide leadership for the development of interdisciplinary, science-based solutions to body weight- and health-related problems, with a current focus on the prevention of pediatric overweight

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http://www.cnr.berkeley.edu/cwh

• Literature reviews and synthesis

• School-based intervention studies

• Resources and materials for communities

• Conducting and translating epidemiologic studies

• Community-based intervention studies

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http://www.cnr.berkeley.edu/cwh

Berkeley

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San Francisco

Berkeley Longitudinal Nutrition Study (BLNS)

Aim: To examine the development of childhood obesity from birth to 5 years

Design: Longitudinal study

Measurements: Anthropometry, food and activity records and interviews, lipid profiles, underwater weighing.

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Berkeley Longitudinal Nutrition Study Retention

Year Visit Participants (n)

1969 6 months 450

1970 1 year 386

1971 2 years 312

1972 3 years 270

1973 4 years 242

1975 6 years 186

1985 16 years 180c enter fo r

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1980’s

Overweight among black women was significantly higher than among white women and they experienced higher CVD mortality rates.

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NHLBI Growth & Health Study (NGHS)1987-1992

(funded by National Institute of Heart, Lung & Blood, NIH)

Aim: to track the development of obesity and other cardiovascular risk factors and to identify biological, social and psychological correlates of these risk factors.

Measurements: diet, physical activity, anthropometry, self esteem and other psychosocial factors, blood pressure, lipids, glucose, insulin, health beliefs and attitudes, and family environment measures

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General Description of NGHS

• Design: – Prospective multi-site

biracial cohort study• Subjects: 2379 girls

– 1213 black– 1166 white

• Ages: 9-10 years at baseline

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Locations

• Richmond, California

• Cincinnati, Ohio

• Washington, DC area

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Berkeley

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San Francisco

Richmond

Richmond, California*

• Population: ~100,000

• 16% of the population below poverty line

• High unemployment approaching 10%

• Over 1,000 violent crimes/year

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Recruitment Strategies• Richmond: census sample of girls

enrolled in schools encompassed

by Richmond Unified School District• Cincinnati: Sampled at school level• Washington, DC area: random sampling of HMO

members with a few added volunteers.

Year Age

Retention Rate (%)

Richmond (n=887)

Cincinnati (n=871)

Wash. DC (n=621)

Total (n=2379)

1 9 to 10 100 100 100 100

3 11 to 12 93.1 92.4 96.3 93.7

5 13 to 14 85.9 83.1 91.8 86.4

7 15 to 16 85.2 77.4 83.9 82

9 17 to 18 93.3 80.9 88.6 87.6

10 18 to 19 93 81 90 88

NGHS Retention Rates by site

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Richmond Cincinnati Wash. DC

Refused 1.3 9.1 4.7

Not responsive 0.7 3.6 3.1

Not located 2.5 4.5 0.2

Distance 1.7 1.7 1.1

Other 0.5 0.2 2.4

Total not seen 6.7 19.1 11.5

Percentage of girls not seen by reason by site

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Minimizing Attrition

• External validity

• Internal validity

• Statistical power

Prevention of Attrition

• Recruitment strategies

• Traditional retention strategies

• Key to success: enhanced strategies

Traditional Strategies – to Prevent Attrition

Communication  (7) 

Phone calls; directory assistance

Letter; mail forwarding or certified mail

Family and friend contacts

Tracking (5)Private investigators, police department, social services, post office, driver's licenses, employment records, job, school, hospital and online databases

Incentives (4) Cash, gifts, lottery, raffles

Special Methods  (1) 

Send birthday cards, check in often, organize events for participants

Educate participants

Provide transportation

StaffCharacteristics (1)

Health promotion skills and knowledge and continuity of staffRefs: Aylward 1985; Goldman 1982; Gwadz 1992; Katz 2001; Lloyd 1999; Orr 1992; Pirie 1989; Psaty 1994; Senturia 1998

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CommunicationIncentives

Special Methods

Staff Characteristics

Tracking

Traditional Strategies to

Prevent Attrition

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Incentives Communication

Special Methods

Staff Characteristics

TrackingDevelop refusal

conversion system

Pilot test

Communicate values,

expectations, plans, etc.

Develop comprehensive

tracking system

Keys to Success

Hire culturally sensitive, respectful,

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1. Staff Hiring

• Culturally sensitive• Flexible• Respectful• “Customer” is always right

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2. Development of Tracking Systems

• Annual update and expansion of contact information

• Call records• Hire a sleuth, problem

solving, obsessive-compulsive interviewer

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_________________________________________________TRADITIONAL CALL RECORD for Participant 1181 – Luann Stipes_________________________________________________

1/9/98 — No answer.1/10/98 — No answer.1/12/98 — Called parents. No answer.1/14/98 — Called parents. Wrong number.

Called mother-in-law who said Luann has moved back Antioch. Her phone number there is (555) 573-2730.

1/15/98 — Called Luann. No answer.1/16/98 — Reached Luann and scheduled her for Saturday,

Jan. 27th at 11 am. Need to mail directions and date/time of appointment.

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CALL RECORD for Alicia Green 400 39th St., Richmond, CA 94804 -(510) 777-5010

3/4/98—1:35 pm—666-7777 is disconnected.Tried father at (510) 888-9999. Left no message on answering machine.5:40 pm—Called father’s number and reached Alicia’s brother. She does nothave a phone, can be reached through this number. He said he’d relay a message. He said she can be reached at this number between 1 and 3 pm. I told him I’d try tomorrow. He said he’d relay the message.

3/5/98—1:00 pm--busy signal1:20 pm—Reached Alicia. She is living with Dad and about to move into her own house. Seemed pleased to hear from me. Cooperative. busy now, but call next week.

3/12/98—1:30 pm—Answering machine, did not leave message3/13/98 - 4:00 pm—Reached brother. Alicia has moved to own place. Got her phone number, 111-2222. Number is not in service.3/14/98—7:00 pm—Tried Alicia’s number again. Still not in service. Called brother; reached

father this time. He doesn’t have number for Alicia. Also says he doesn’t have her new address. Says I can call tomorrow morning at 10:00 am.

3/15/98—10:05 am—Reached brother. Alicia does not have a phone. Gave me her address: 2121 5th Street in Richmond. Sent Alicia a note with my phone number, asking her to call me.3/29/98—6:00 pm—Went to Alicia’s address. She was home and very happy to hear from us

again. Scheduled her for clinic on 4/7 at 11:00 am. She is happy to have her own place, lives with her son. 4/7/98—Alicia came to clinic. Everything went well. Really cute little boy, named DeVonne.

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3. Pilot Testing

4. Development of a Refusal Conversion System

• Hire/designate a specialist

• Use all information from past call records

• Take participants’ reservations seriously

• Minimize number of contacts

• Take the long view on participation

• Empathize, listen

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5. Communication

• Plan for retention, revise as needed

• Share what works

• Values, study goals, results

• High expectations

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Incentives Communication

Special Methods

Staff Characteristics

TrackingDevelop refusal

conversion system

Pilot test

Communicate values,

expectations, plans, etc.

Develop comprehensive

tracking system

Key to success:

leadership

Hire culturally sensitive, respectful,

flexible staffc enter fo reight &

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Study Leadership

• Plan and budget recruitment, tracking, cohort retention, refusal conversion

• Hire culturally sensitive interviewers with excellent communication skills

• Designate (or hire) specialized tracker and refusal converter staff

• Develop protocols and train staff

• Communicate with staff your values including respect, flexibility, and high expectations

• Celebrate every participant victory

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Using these methods ...Race White Black

  NS 87% 88%

Site Richmond CincinnatiWashington

DC

p<.001 93% 81% 90%

Household Income Low Middle Upper

p<.01 85% 89% 90%

BMI Mean for those retained 18.58

NS Mean for those lost to follow-up 18.51c enter fo r

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Comparison of subjects retained and lost (Year 10)

NGHS Follow-up Studies

Follow-up Study Site

End Date

Original Cohort

Follow-up

Retention Rate

Fibromylagia and TMD Berkeley 1989 887 830 94%

Eating Disorders All sites 2001 2379 2046 86%

Pregnancy Berkeley 2003 330  301  91%

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We streamlined the human subjects protection forms by

using handwritten coversheets:Streamline the

human subjects protection forms by using handwritten

coversheets

In order for your child to participate in the Growth and Health Study this year, you must sign the green consent form and return it to your child’s school before Thursday, October 15th.

Thank you, Pat Crawford

Project Directorc enter fo r

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Our blooper:

Streamline the human subjects

protection forms by using handwritten

coversheets

I order for your child to participate in the Growth and Health Study this year, you must sign the green consent form and return it to your child’s school before Thursday, October 15th.

Thank you, Pat Crawford

Project Directorc enter fo r

eight &ealthh University of California, Berkeley

Thank you

Sheila Stern

Sarah Krathwohl

Zak Sabry

NHLBI

and all of the NGHS participants who have given generously of their time for almost 15 years!

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Visit the Center for Weight and Health at http://www.cnr.berkeley.edu/cwh/