Zdrav Var 2007; 46: 1-8
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SLOVENE NATIONAL SURVEY OF SEXUAL LIFESTYLES, ATTITUDES AND HEALTH, 1999-2001: DATA COLLECTION
METHODS
SLOVENSKA NACIONALNA PREČNA RAZISKAVA SPOLNEGA VEDENJA, STALIŠČ IN ZDRAVJA, 1999-2001: METODE ZBIRANJA
PODATKOV
Irena Klavs1, Darja Keše2, Igor Švab3
Prispelo: 8. 6. 2006 - Sprejeto: 18. 12. 2006
Original scientific article UDC 616.9
Abstract
Aim: A national survey on sexual lifestyles, attitudes and health, including integrated testing for Chlamydia trachomatis genital infection in a probability sample of Slovene men and vvomen aged 18 to 49 years, was conducted to inform sexual and reproducive health policies on this issue. Particular attention was devoted to reducing measurement errors. The data collection methods are presented.
Methods: The field work for the cross-sectional study was conducted betvveen 1999 and 2001. An \ntroductory letter was sent to the selected individuals. Data were collected in respondents’ homes through a combination of face-to-face intervievvs and anonymously self-administered questionnaires (pencil and paper). Respondents were asked in advance to seal the anonymously completed booklets themselves. The survey methods were adapted from the equivalent British survey conducted in 1990. Respondents were invited to provide a first void urine (FVU) specimen for polymerase chain reaction testing for C trachomatis. Specimens were frožen on the day of collection, stored at -2CPC, and transported to the laboraton/ in cold boxes every two vveeks. To contain cost, a pool size of five samples was used for polymerase chain reaction testing. Individuals diagnosed with C. trachomatis infection were referred for treatment.
Conclusion: The data collection methods used in the restrained-resource setting proved very good. Possible limitations include validity constraints of self-reported Information, yet anonymous self-administration of more sensitive questions probably contributed to improved validity The methods for the transport, storage, and testing of urine specimens were sufficiently robust to ensure high sensitivity and specificity of laboraton/ results.
Key words: sexual behaviour, sexually transmitted infections, Chlamydia trachomatis, human immunodeficiency virus, survey methods, general population, Slovenia
Izvirni znanstveni članek UDK 616.9
Izvleček
Cilji: Za poučeno spolno in reproduktivno zdravstveno politiko je bila v verjetnostnem vzorcu slovenskih moških in žensk, starih 18 do 49 let, izvedena nacionalna prečna raziskava spolnega vedenja, stališč in zdravja z vključenim testiranjem na genitalno okužbo z bakterijo Chlamydia trachomatis. Veliko pozornosti je bilo namenjene omejitvi napak pri merjenju. Predstavljene so metode zbiranja podatkov.
Metode: Terensko delo prečne raziskave je bilo izvedeno v letih 1999-2001. Izbrane osebe so prejele napovedno pismo. Podatki so bili zbrani na domovih sodelujočih s kombinacijo anketiranja v osebnem stiku in anonimnega samoizpolnjevanja vprašalnikov (svinčnik in papir). Sodelujoči so bili vnaprej obveščeni, da bodo sami zalepili
1AIDS, STI and HAI Unit, Communicable Diseases Department, Institute of Public Health of the Republic of Slovenia, Trubarjeva 2,
1000 Ljubljana, Slovenia
2Institute of Microbiology and Immunology, Medical Faculty, University of Ljubljana, Zalo{ka 4, 1000 Ljubljana, Slovenia 3Department of Family Practice, Medical School, University of Ljubljana, Poljanski nasip 58, 1000 Ljubljana, Slovenia
Correspondence to: e-mail: irena.klavs@ivz-rs.si
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izpolnjene anonimne knji‘ice v kuverte. Metode so bile prirejene po podobni britanski raziskavi, ki je bila izvedena leta 1990. Sodelujo~i so bili povabljeni, da prispevajo prvi curek urina za testiranja s polimerazno veri‘no reakcijo na oku‘bo z bakterijo C trachomatis. Vzorci so bili zamrznjeni na dan odvzema, shranjeni pri –200 C in na 14 dni prepeljani v laboratorij v hladilnih torbah. Zaradi prihranka je bil po en test s polimerazno veri‘no reakcijo izveden na pet zdru‘enih vzorcih. Osebe z oku‘bo z bakterijo C. trachomatis so bile napotene na zdravljenje. Zaklju~ki: V okoli{~inah z omejenimi sredstvi so bili podatki metodolo{ko zelo dobro zbrani. Mo‘ne omejitve vklju~ujejo vpra{ljivo verodostojnost podatkov, ki jih poro~ajo sami anketiranci, vendar je anonimno samoizpolnjevanje odgovorov na bolj ob~utljiva vpra{anja verjetno prispevalo k ve~ji verodostojnosti. Metode prenosa, hranjenja in testiranja vzorcev urina so bile dovolj stroge, da so zagotovile visoko ob~utljivost in specifi~nost laboratorijskih rezultatov.
Klju~ne besede: spolno vedenje, spolno prenosljive oku‘be, Chlamydia trachomatis, virus ~love{ke imunske pomankljivosti, metode pre~ne raziskave, splo{no prebivalstvo, Slovenija
1 Introduction
To formulate appropriate and effective sexual and reproductive health policies, including prevention and treatment of sexually transmitted infections (STI) and infections with human immunodeficiency virus (HIV), it is crucial to understand sexual behaviour of the population and epidemiologv of STI and HIV. Yet, no national sexual behaviour survev had been conducted in Slovenia by 1999. Two fertility survevs failed to collect adequate information on the sexual behaviour patterns relevant to STI and HIV epidemiology (1-3). Genital infection with Chlamydia trachomatis is the most common curable STI in Slovenia (4). In most infected vvomen and in a large proportion of men, symptoms of C. trachomatis infection are minor or absent (5-10). This large group of asymptomatic and infectious persons sustain transmission in the community. Studies of convenience samples in the Slovene health čare settings reported a prevalence of 6% to 16.5% among asymptomatic vvomen, and of 2.7% to 3.2% for asymptomatic men (11-14). Ali these estimates vvere subject to selection bias. No prevalence estimate based on a probability sample of the general population had been made available by 1999.
To fill these gaps, the Institute of Public Health of the Republic of Slovenia (IPHRS) conducted the first national survey of sexual lifestyles, attitudes and health related to HIV and other STI, vvith integrated testing for C trachomatis genital infection. To ensure valid survey results, particular attention vvas devoted to reducing potential survey errors, including the measurement errors (15).
The aim of this article is to present the data collection methods used, to discus their strengths and limitations, and compare them to the methods used in similar survevs.
2 Survey methods
2.1  Reference population and sampling strategy
The cross-sectional study population consisted of Slovene citizens aged 18 to 49 years residing in Slovenia. The details of our stratified tvvo-stage probability sampling, survey response, data vveighting, and sample representativeness vvere published previously (16). Briefly, vve used stratified tvvo-stage probability sampling of 18-49-year-old persons vvith oversampling of the 18-24-old age group.
2.2 Recruitment and training of intervievvers
The fieldvvork vvas started in September 1999 after vve had obtained funds to intervievv approximately 1,000 individuals, and had prospects to obtain funding to intervievv additional 1000 individuals. Altogether 39 female intervievvers vvere recruited from the pool of intervievvers of the Statistical Office of the Republic of Slovenia and trained by the principal investigator, the first 22 at a full day vvorkshop in November 1999, and since it appeared difficult to follovv the very intensive full day training, the remaining 17 in tvvo half days vvorkshops, in February and March 2000. Intervievvers vvere instructed on hovv to conduct intervievvs as described bellovv, and encouraged to provide reassurance during the initial contact. The need
Klavs I.,   Keše D., Švab I. Slovene national survey of sexual lifestyles, attitudes and health, 1999-2001: data collection methods______3
for confidentiality was stressed and information was provided on how to appropriately inform the person to obtain informed consent. The procedures to ensure anonymous collection of most sensitive information while stili preserving the link betvveen ali information reported by each individual were explained. The intervievvers were urged to insist on conducting the intervievv in privacy. To encourage respondents to ansvver honestly and to prevent mistakes, the greatest emphasis was placed on role-playing the introduction of anonymous questionnaires for self-completion. VVithin a week after the training and after the first few intervievvs were conducted, the principal investigator visited aH intervievvers and provided individual feedback on vvhether the first fevv intervievver-administered questionnaires and ali other forms vvere completed correctly. The skills to introduce the self-administered booklets vvere reassessed and reinforced.
2.3 Advance letters
Before the visit of the intervievvers, ali selected individuals received an advance letter explaining the survey goals, and informing them that they had been randomly selected from the general population and invited to participate. The letter included information about the collaborating institutions and funding agencies. It vvas pointed out that more intimate details vvould be collected anonymously, and that for the success of the survey it vvas important for each invited individual to contribute his or her ovvn experiences and attitudes, whatever they may be.
2.4 Intervievving procedures
The intervievving procedures vvere adapted from the British National Survey of Sexual Attitudes and Lifestyles (NATSAL) conducted in 1990 (17). They vvere pre-tested and piloted in a feasibility study (18). The methods vvere very similar to those used in the second British NATSAL conducted in 2000 (19). At least five calls at different days of the vveek and at different times of the day vvere made before an address vvas considered as a non-contact. Details of ali visits to the selected addresses, their outcome, and information on the ascertained residence status vvere entered in visit record forms.
At the doorstep, intervievvers introduced themselves and shovved their intervievvers’ ID card bearing their photograph and the name of the survey . Permission to briefly explain the study aims vvas asked for. Respondents vvere invited to read a short leaflet providing general information about the study and hovv
they vvere selected. It assured them that most intimate questions vvould be ansvvered anonymously and that they had the right to refuse to participate in the study, to interrupt the intervievv at any point or just not to ansvver an individual question. The leaflet also listed the intervievvers’ professional duties, and provided information about the research team, the participating institutions, and the funding sources. The research team address vvas given at the end, in čase further information vvould be sought. The leaflet vvas left vvith the respondent. Additional explanation vvas provided only upon request. As it vvas anticipated that some individuals vvould claim that their particular sexual lifestyle vvas not relevant for such a survev, the intervievvers vvere instructed to stress the necessity to capture ali the diversity of specific lifestyles and attitudes, whatever they may be, from as many selected individuals as possible in order to get the most accurate possible results, valid to the population as a vvhole. After verbal informed consent had been obtained, intervievving started vvith less sensitive intervievver-administered questions about health, family and religious affiliation, vvhich facilitated the development of good rapport. Then, shovv cards vvith letter pre-coded ansvvers vvere introduced to facilitate the ansvvering of more sensitive questions asking about sources of information on sexual matters and age at first heterosexual experience and information about first heterosexual intercourse. This presumably resulted in less discomfort for respondents as vvell as intervievvers, as possibly embarrassing sex related vvords vvere avoided by using letter codes for ansvvers. Respondents vvho reported their age at first heterosexual intercourse vvere asked several questions about the event. A great majority vvere intervievved face-to-face. An alternative to completing a self-administered booklet vvas provided, if intervievvers judged that it vvas not private.
Respondents vvho reported their age at first heterosexual intercourse or some other sexual experience vvere invited to complete anonymously four self-administered questionnaires in the presence of the intervievver. Sexual experience vvas defined as any kind of contact vvith another person that respondent felt as sexual (e.g. kissing, touching, intercourse, or any other form of sex). The booklets included questions about sexual behaviour, injecting drug use, and history of STI. Each of the four booklets vvas briefly introduced. To prevent mistakes, instructions included hypothetical examples about hovv to ansvver the most important and the most difficult questions and hovvto skip inappropriate questions. It vvas stressed in advance, that intervievvers
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would not see the ansvvers, but would be vvilling to provide additional explanations by hypothetical examples and using another empty questionnaire. Respondents were told in advance, that they would themselves seal the anonymously completed booklets in envelopes with the IPHRS logo. The intervievver-administered questions about attitudes of the respondents follovved. The aim of this sequence was to minimize social desirability bias for the anonymously reported behaviour. For example, if in a face-to-face intervievv the respondents were asked earlier vvhether they approve of extramarital affairs or not, they might be less likely to report such behaviour, if asked about it aftervvards. The intervievvs concluded with questions about demographic and social characteristics, the information least likely to be reported inaccurately at the end of a rather long intervievv.
Finally, respondents vvere thanked for their important contribution and given tee shirts vvith the IPHRS logo, a symbolical revvard for the tirne and effort they spent on the task. This timing, just before asking for a urine specimen, vvas intentional and aimed at increasing the urine specimen contribution rate.
2.5 Ensuring anonymity of intimate information
AN intervievvers received a list of as many randomly selected unique numbers as addresses of the individuals selected. They vvere instructed to use one of these unique numbers to link the intervievver-administered questionnaire and the self-administered questionnaires for each respondent. The questionnaires did not contain identifying information. In contrast, forms to record visits to the selected individuals’ addresses and their outcomes contained identifying information about respondents as vvell as non-respondents, but the allocated respondents’ unique numbers vvere not recorded on these. Tvvo data sets, the visits’ records data set and the main data set, including information reported confidentially and anonymously by respondents, vvere entered separately at tvvo different locations, at the IPHRS and at the CATI Centre Ljubljana. Thus, the identity of each respondent vvas unlinked from the demographic, behavioural and attitudinal information reported.
2.6 Collection and storage of urine specimens
After the intervievv, respondents vvere asked for additional fevv minutes of their tirne ; they vvere invited to participate in the extended study by contributing a urine specimen to be confidentially tested for C.
trachomatis. They vvere offered to read a letter explaining the aims of such testing. The letter stressed confidentiality of testing results and pointed out that in the čase of a positive result, the respondent vvould be notified vvithin a month and referred for treatment. If the respondent agreed to the proposed testing, the informed consent form vvas signed, and instructions vvere given on hovvto obtain a FVU specimen. Each specimen vvas labelled vvith the unique respondent identifying number. Both the unique identifying number and the respondenfs name vvere entered in a laboratory report form, hovvever, on tvvo different parts to be separated later. AN specimens vvere transported in cold boxes to intervievvers’ homes vvhere they vvere frožen on the day of collection and stored at -20°C in small freezers provided for this purpose.
2.7 Transport of urine specimens and data from the field, and field work supervision
Frozen urine specimens vvere collected from intervievvers’ homes every tvvo vveeks and transported to the laboratory in cold boxes. Signed informed consent forms for urine specimen collection, laboratory forms, completed questionnaires, reports on visits, forms giving temporary addresses or nevv permanent addresses to be reallocated to intervievvers vvorking in respective areas, and reports on the number of completed intervievvs, collected urine specimens and mileage vvere collected at the same tirne. These regular visits of the principal investigator or another member of the research team made it possible to monitor closely the field vvork progress and to address any intervievvers’ queries in a timely manner.
2.8 Laboratory testing for C. trachomatis
AMPLICOR polymerase chain reaction (PCR) tests for C. trachomatis vvere performed on thavved FVU specimens according to the manufacturer’s instructions (Roche Diagnostic Systems, Basel, Svvitzerland) (20). The AMPLICOR internal control detection vvas also included in the PCR assay according to the producer’s instructions to identify inhibitor/ specimens and assure the integrity of negative results (21-23). To contain test costs, pooling of urine specimens in groups of five vvas used (24, 25). Specimens from reactive pools vvere re-tested individually.
After recording the test result on both parts of the laboratory report form, the tvvo parts, one vvith the unique identifying number and the other vvith the name of the respondent, vvere cut in tvvo. The parts vvith unique identifying numbers vvere sent to the Ljubljana CATI
Klavs I.,   Keše D., Švab I. Slovene national survey of sexual lifestyles, attitudes and health, 1999-2001: data collection methods______5
Centre to be anonymously linked with demographic, behavioural and attitudinal information reported by respondents. The parts with respondents’ identifying information were sent to the IPHRS for confidential notification of infected respondents and analysis of the participation in urine specimen collection.
2.9 Notification of infected individuals
Individuals diagnosed with C. trachomatis infection were sent a letter notifying them about the positive result. Men were referred for treatment to their general practitioner and women were advised to choose betvveen their general practitioner and gynecologist. In addition to the details about the test result the letter included recommendations for treatment, some information about the survey and a suggestion that contacts should be notified and treated, which was partly intended to guide the treating physicians. Charge free čase management according to the recommendations of the Centers for Diseases Control and Prevention that included counseling and contact notification was offered at the Central Dermato-venerological outpatient clinic in Ljubljana, if preferred (5).
2.10 Time frame
The first series of intervievvs was started in November 1999 and covered the central, northern, and north eastern parts of Slovenia, and the second series of intervievvs in the rest of the country vvere started in February 2000. This geographical split simplified the logistics of the transport of urine specimens and other survey materials from the field, and reduced the costs of storing frozen FVU specimens at intervievvers’ homes, as the refrigerators used in the first series could be reallocated to different intervievvers conducting the second series of intervievvs. The last six intervievvs vvere conducted in 2001, the very last one in February. This long fieldvvork also made it possible to obtain the funding from the Ministn/ of Health during tvvo consecutive fiscal years.
2.11  Ethical clearance
The Medical Ethics Committee at the Ministn/ of Health of the Republic of Slovenia consented to the proposed study on 17 October 1997, under the condition that more sensitive information vvas acquired anonymously. In addition, ethical clearance of the London School of Hygiene and Tropical Medicine Ethics Committee vvas obtained in December 1999.
3 Discussion
Various data collection methods vvere used in the national HIV and STI-related sexual behaviour survevs. Face-to-face intervievving vvas used in surveys coordinated by theVVorld Health Organization, and in the Netherlands (26, 27). Self-administering questionnaires vvere used in Germany and Spain, and postal survevs in Norway and Croatia (27-30). Postal self-administered short module on sexual behaviour vvas attached to the face-to-face fertility survey in Slovenia in 1996, but the response rate vvas very lovv (belovv 50%). Computer-assisted telephone intervievving (CATI) vvas used in Belgium, France, Germany, Scotland, Svvitzerland and in the US (27, 31-34). A combination of face-to-face intervievv and self-administration of more sensitive questions vvas used in the first survey conducted in Britain, Finland, Germany, Portugal and the US (17, 27, 35). The second British national survey used combination of computer-assisted personal intervievv (CAPI) and computer-assisted self-intervievv (ČASI), vvith respondents keying responses to questions displayed on the screen (19). It has been shovvn that respondents are more vvilling to reveal socially censured information in confidentially self-administered questionnaires or video-CASI than in face-to-face intervievvs (36). Studies comparing ČASI vvith pencil and paper self-administration of identical questions demonstrated the potential of ČASI to improve the quality of data and to increase respondents’ vvillingness to report sensitive behaviours (37). In contrast, the pilot study for the second national British survey found no evidence that ČASI increased the reporting of risk behaviour vvhen compared to pencil and paper self-administration of the same questions, but did demonstrate improved item response and data consistency (38). Audio-CASI has been reported to be superior in capturing sensitive sexual behaviour data and information on injecting drug use in the U.S. adolescent population in comparison to pencil and paper self-administering technique, and also in capturing HIV risk behaviour among injecting drug users in comparison to CAPI and ČASI (39, 40). In our setting of constrained resources, vve decided to adapt the data collection method used in the national Sexual Attitudes and Lifestyles Survey conducted in Britain in 1990 and 1991, a combination of face-to-face intervievv and self-administration of more intimate questions using pencil and paper (17). The method vvas pre-tested and used successfully in the feasibility study (18). Hovvever, piloting ČASI or audio-CASI and comparing it to the pencil and paper self-administering technique should
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be considered vvithin preparations for any future national sexual behaviour survey in Slovenia. In spite of ali our efforts to improve the validity of the data obtained, possible limitations of our survey include validity constraints on self-reported sexual behaviour data that are inherent in ali such surveys. Missreporting of sexual behaviour has been documented (41-43). Nevertheless, we believe that we managed to improve the veracity and thereby the validity of self-reported information on higher-risk sexual behaviour by providing the possibility of anonymous self-administration. Yet it is impossible to conclude from our results what the contribution of anonymity was in addition to self-administration. Some participants explicitly praised the provision of anonymity in pre-testing and stated that they felt more vvilling to disclose intimate information. A comparison of information reported face to face with that reported anonymously in self-administered questionnaires shovved that anonymous self-administration captured some higher-risk sexual behaviour better than face-to-face intervievving. So nearly one in ten men and one in twenty vvomen, who reported only one lifetime heterosexual partner during the face-to-face intervievv, reported several in the anonymous self-administered questionnaire. Also, only half of respondents who reported some homosexual experience in the self-administered questionnaire did so when intervievved. Hovvever, the great majority of those who anonymously reported penetrative homosexual sex did teli intervievvers that they had some homosexual experience.
We are confident that the type of specimens we collected, freezing specimens on the day of collection for storage, maintaining cold chain during storage and transport to the laboratory, and testing thavved specimens using PCR, ensured high sensitivity and specificity of our laboratory results (44-47). To circumvent the possible problem of FVU specimens containing inhibitors for PCR assay (48-50) and to ensure the validity of negative results, we used the internal control incorporated in the Amplicor PCR kit to identify inhibitory specimens. Based on previous reports (24, 51), we assume that sensitivity was not affected by PCR testing in pools of five urine specimens. In contrast, British researchers reported that they may have underestimated C trachomatis prevalence, as some loss of sensitivity may have occurred due to delays in specimen transport (52). In conclusion, strengths of our survey methods included the use of well-tested and piloted data collection methods, a combination of face-to-face
intervievvs and anonymously self-administered questionnaires (pencil and paper), adapted from one of the best national general population sexual behaviour survevs, the British NATSAL 1990 (17,18). In addition, high response rate and representativeness of our survey sample contributed to the validity of our results. Possible limitations included validity constraints of self-reported information common to ali such survevs. Hovvever, vve believe that in addition to self-administration, the possibility to ansvver the most sensitive questions anonymously contributed to improved validity of our data. It is possible that some other data collection method, e.g. ČASI, vvould prove superior in capturing sensitive behaviour information. Our methods used for the transport, storage and testing of FVU specimens vvere robust enough to ensure high sensitivity and specificity of the laboratory results obtained.
The results of our survey have and vvill provide useful information to those vvho vvork in the delivery of reproductive health policies and HIV and STI prevention, and in the formulation of control strategies. So, the steep increase in condom use at first heterosexual intercourse suggests that HlV-related condom use promotion has had an impact (16). In contrast, a relatively high prevalence of genital C trachomatis infection among 18-24-year old Slovenians, in the presence of relatively lovv risk sexual behaviour and lovv reported incidence rates of chlamydial infection, suggest serious gaps in the diagnosis and treatment of the condition (53).
Acknovvledgement
We thank the respondents; the intervievvers; Laura C Rodrigues, Kaye VVellings and Richard Hayes for contributing to the design of the study; Marta Arnež, Zdenka Blejec, Marta Grgič-Vitek, Zdenka Kastelic, Andrej Kveder, Marjan Premik, and Metka Zaletel for contributing to the survey implementation.
Contributors:
Irena Klavs, the lead author, designed and coordinated the implementation of the study, and analysed and interpreted the results. Darja Keše coordinated the laboratory testing and participated in the preparation of this paper. Igor Švab contributed to the design of the study and participated in the preparation of this paper.
Klavs I.,   Keše D., Švab I. Slovene national survey of sexual lifestyles, attitudes and health, 1999-2001: data collection methods______7
Conflict of interest: None.
Sources of support:
The study was supported by grants from the Ministry of Health, Ministry of Science and Technology, Ministry of Education, Science and Sports, City Council of Ljubljana, Health Insurance Institute of Slovenia, Mere & Dohme Idea Inc., Roche Diagnostics, Krka, and Lek. Running head: Slovenian sexual behaviour survey methods
List of abbreviations:
CAPI             - computer assisted personal intervievving
ČASI            - computer assisted self intervievving
CATI             - computer     assisted     telephone
intervievving FVU              -  first void urine
HIV               - human immunodeficiency virus
IPHRS          - Institute of Public Health of the Republic
of Slovenia NATSAL       - National Survey of Sexual Attitudes and
Lifestyles PCR             - polymerase chain reaction
STI               - sexually transmitted infections
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