Using respondent-driven sampling to recruit PWID in eight large cities in Germany

The 2011-2014 DRUCK-Study

EMCDDA PDU Expert Meeting Lisbon, 8-9 June 2017

Stine Nielsen (stine.nielsen12@gmail.com)

@StineNielsenEPI

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Outline

Objectives

Background

RDS

Methods + logistics

What did we do and how did we do it

What did it cost

Some results – who did we reach?

Lessons learned and would we do it again?

Where to learn more about RDS & the DRUCK-study

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Objective of this talk

To describe the methods and practical aspects of the respondent driven sampling (RDS) study that was conducted among PWID in Germany from 2011-2014

Focusing on lessons learned for other countries who might consider using this methodology

The study was done by the Robert Koch Institute – the national institute for public health in Germany

In collaboration with several partners at national and local level such as low threshold drug services (LTS), “Deutsche AIDS-Hilfe” and more

Question: How many have heard of respondent driven sampling?

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Background

No routine monitoring system in place in Germany to monitor infections or risk/preventive behaviors among PWID

In 2011, the Robert Koch Institute initiates the pilot of the “DRUCK”-study: Drogen und chronische Infektionskrankheiten

Main objectives of the study:

Primary: Generate data on sero-prevalence of HIV, HCV and HBV as well as data on risk and preventive behaviors among people who injected drugs (PWID) in the last 12 months in order to improve (infectious disease) prevention efforts

Secondary: Collect data to inform how best to setup future monitoring incl. establishing a network of facilities and partners

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Why respondent driven sampling (RDS)

So far only convenience based sampling – recruiting drug users in OST-facilities, detoxification units, drug consumption rooms or needle-exchange programs

Mostly local, relatively small and few recent studies of infections and risk/preventive behaviors among PWID in Germany

RDS proved to be an effective method to rapidly recruit well-networked groups like PWID

>460 studies published globally – many have used it to recruit PWID

We used respondent driven sampling (RDS) as a recruitment strategy to try and reach those not in regular contact with existing services

A more representative sample of drug users

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Respondent driven sampling (RDS)

Introduced in 1997 by Heckathorn et al as a modified snowball method to recruit hard-to-reach populations

Popular method to recruit PWID due to their strong social networks RDS has worked well as a recruitment method in most studies

Begin with a set of ‘seeds’ (initial participants)

Seeds recruit peers, who recruit peers, etc.

Recruits are linked by coupons with unique identifying numbers

Incentives provided for completed survey and for each successful recruit

10€ participatio, up to 3x5 € for participants recruited

For weighted analysis:

Serial numbers (respondent + recruiter)

Personal network size

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RDS theory: State of equilibrium

= the stabilization of the sample composition after a sufficient number of “waves” (recruitment rounds) - hereafter, even if more people are recruited the characteristic proportions remain stable – defined as when sample distribution (age, sex, infection status) changed <2% from one wave to the next

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Selecting seeds (initial recruits)

Seeds (initial recruits) selected in collaboration with local study partners (low threshold drug services, LTS)

Characteristics: Gender, country of birth, residential area, preferred LTS, preferred substance, self-reported HIV status, sex work and imprisonment experience. + expected willingness to participate and recruit others

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Defining the population of PWID

Ever injecting

Recent injecting

In OST

The DRUCK-study focus on people injecting in the last 12 months regardless of contact to services (OST, NEP, DCR etc.) Inclusion criteria: Aged 16y+ & injecting in the study city in the last 12 months

Methods

Zimmermann et al, BMC Public Health 2014

Study sites: • Mapping • geographic diversity • 8 cities • Calculated sample size: 2,033

• Target: 200-350 participants per city

• Low treshold drug services

• Drug consumption rooms • Needle-exchange • Drop-in / Cafe • Youth center • OST • Homeless shelter 1-4 per city

Data collected

Capillary dried blood spots (DBS) anti HIV

anti HCV + HCV-RNA

anti HBs, anti HBc, HBV-DNA + (HBsAg)

Questionnaire-assisted interviews

trained interviewers sociodemographics, used substances, unsafe use, sex,

imprisonment, knowledge, health status, testing history

Based on EMCDDA/UN indicators

30-45 min. interview

anonymised

Minor modifications after pilots

Ross et al, Virology Journal 2013

Interventional parts of the study

HIV-rapid testing offered to participants

- in supplement to DBS testing

Targeted counselling in low-threshold drug services

- Short and targeted counselling for knowledge gaps during interview

- Training of counsellors

HIV/ Hepatitis C – test results

• Provided after 2 weeks during study opening hours

• Posttest-counselling by trained MD

DRUCK-Studie des Robert Koch-Instituts

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Study flow-chart for participation

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Close collaboration w local partners

Pre-meeting with multiple stakeholders in each city – early phase of planning

Low threshold drug service – sometime several partners

Local health service – linkage to care

Police, politicians, addiction services

Study team recruitment and contracts with local partners

2-day training in each city

Post-data collection: Evaluation meeting (gathering lessons learned)

Report with local data and dissemination meeting

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2-day training of the study teams in each city

Key members of the local study team:

Local study coordinator

Overview of the study flow, obtain informed consent, manage adverse events

Coupon manager

Screen for inclusion criteria, prevent multiple enrollment, provide unique id to each participant, document recruitment, explain recruitment process to participants, pay incentives

Interviewers – often several at a time (translation possible)

Counsellors – provide voluntary counselling for for viral hepatitis and HIV

Lab person – collecting dried blood spots and performing rapid HIV tests

Doctor on call – post-test counselling & venous blood if reactive rapid test

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Time line of the study

2011: RKI funded pilot study – 2 first cities (Berlin + Essen)

Ministry of Health funding: 1 April 2012 to 31 March 2015 (3 years)

First 6 months:

Ethical approval + “Kick-off” meeting: selecting study cities + finding collaboration partners

20 months (Oct 2012-May 2014): data collection in 6 cities

10 months (June 2014 – March 2015):

Data cleaning + validation

Analysis

Report to participating cities

Dissemination meeting w multiple stakeholders

Final report to Ministry of Health

Published 1 Feb 2016 (275 pages)

Preparing international peer-reviewed publications

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DRUCK-teams at RKI

Epi team

Lab team

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Funding of the DRUCK-study

2011 (2 pilot cities and lots of preparation) = RKI funding

3 years of funding from Ministry of Health (BMG) – 2012-2015

≈ 400,000€ for RKI staff

≈ 120,000€ for the local partners (6 cities)

≈ 160,000€ for lab costs (staff & tests), incentives, meetings, trainings

Total: ≈ 680,000€ for the last 3 years

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Results

9 – 31% 18 – 35% 2 – 27%

Women Not born in Germany

Younger than 25 years

Ever in prison Ever homeless

53 – 77% 73 – 86%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% N=2.077 Age (Median): 29-41 years

Sociodemographic characteristics Range of each of the eight study cities

14.12.2016 20 Fachaustausch zur DRUCK-Studie

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Characteristics of participants Range in the 8 study cities (N=2077)

76-88% injected in the last 30 days

17-39% injected daily

Median years of injecting: 10-18 years

31-66% were currently in opioid substitution therapy (OST)

79-91% visited a low threshold drug service in the last 30 days

77-95% saw a doctor in the last year

HIV: 0-9.1%

HCV AB+: 42-75% - chronic infection (AB+, RNA+): 23-54%

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Reasons for participating

Multiple answers possible (N=2,050) 64% the money 57% the study is important and interesting 27% the chance to get tested 19% to increase my knowledge 14% the rapid HIV test (not asked in Berlin)

12% my friends/acquaintances are participating 6% I had time and nothing better to do

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Details of recruitment

Berlin N=337

Essen N=197

Leipzig N=130

Frankfurt N=285

Cologne N=322

Hanover N=252

Munich N=235

Hamburg N=319

Recruit-ment period

05-07 2011

10-12 2011

10-12 2012

01-03 2013

04-05 2013

07-09 2013

10-12 2013

03-05 2014

Study sites

4 1 2 2 1 1 1 1

Max waves

13 10 8 20 13 14 14 20

Coupon received from:

partner - - 7% 5% 2% 4% 3% 2%

acquaintance

- - 78% 64% 84% 50% 67% 65%

stranger - - 15% 31% 14% 46% 30% 33%

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Network pictures with infection status

Munich, N=235 Hamburg, N=319

Total “seeds”: 13 9 Unproductive “seeds”: 3 0 Max recruitment waves: 14 20

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Lessons learned & challenges

Importance of good local partners, collaboration with multiple stakeholders, time for training of all study staff

Most PWID reached were in contact with the low threshold services – future plan to establish a routine monitoring system based in these settings – similar to the UAM from the UK.

Challenges:

Estimating the size of the network = difficult Range: 0-1400 individuals

Phrasing and importance of this question

In all cities, we observed a decreased interest in participation in the days following the monthly “social benefit”-payment

Multiple study locations and differing opening hours complicated

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Want to know more about the DRUCK-study?

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Lots of materials about respondent driven sampling

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RDS and population size estimates

Lisa Johnston et al 2013: Incorporating the service multiplier method in respondent- driven sampling surveys to estimate the size of hidden and hard-to-reach populations: case studies from around the world. Sex Transm Dis 2013, 40(4):304–310.

Two different multiplier methods:

“Service multiplier method”

“unique object multiplier”

handed out to target group from facilities NOT used as study sites – e.g. drug treatment clinics, pharmacies, out-reach work prior to data collection

Saying: “It’s possible that you will be asked in the coming weeks to take part in a study. And if so, you will be asked if you received a cigarette lighter like this one”

A record is made of the number of objects handed out (by sex and age-group)

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Points for discussion

A key finding was the heterogeneity between the 8 cities – e.g. in terms of age, migration profile, substances used etc.

We are still working on the best way to deal with the “city-effect” in our interpretation of the data (Input on this very welcome!)

How to assess if the PWID we recruited in this study are representative of all PWID in Germany?

Key points:

Try it! RDS can be a way to recruit people who use drugs – generates important data! E.g. Proportion (%) in contact with services.

Big logistical effort – but very worth it

Excellent for generating a baseline

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Next steps planned in Germany

Establishing a routine monitoring of infections and risk/preventive behaviours among people who use drugs using a network of facilities

perhaps similar to the “Unlinked Anonymous Monitoring (UAM)” from the UK and other places

Planned analysis: Analyse if those not in regular contact with services are different (risk behaviours, substances used, infections etc) than PWID regularly attending low threshold drug services

Thank you! Matthias An der Heiden, Norbert Bannert, Rieke Barbek, Claus-Thomas Bock, Johannes Bombeck,

Birkenstube Berlin, Wei Cai, Deutsche AIDS-Hilfe, Serdar Danis, Kerstin Dettmer, Fixpunkt e.V., Maria Friedrich, Martyna Gassowski, Gesundheitsamt Essen, Osamah Hamouda, Joana Haußig, Claudia Kücherer, Astrid Leicht, Uli Marcus, Bärbel Marrziniak, Sami Marzougui, Stine Nielsen, Doreen Nitschke, NRZ Hepatitis C, Doris Radun, Stefan Ross, Claudia Santos-Hövener, Dirk Schäffer, Suchthilfe Essen, Judith Stumm, Andrea Teti, Benjamin Wenz, Weidong Zhang

cooperating partners in drug services all study participants German MoH (financing partner)

Contact: ZimmermannR@rki.de