The primary objective of the
The secondary objective was to update the prevalence estimates of HBV, HCV, and HIV infections as well as undiagnosed infections in the general population.
Participants were enrolled using the 2016 Health Barometer, a national cross-sectional telephone survey based on a representative random sample of the general population (15,000 individuals) aged 15 to 75 years living in mainland France (
The sampling method for the 2016 edition was identical to that developed for the 2014 Health Barometer [
The 40-minute-long phone survey questionnaire was administered by a trained investigator. It included questions evaluating general health, hygiene and protective habits, sexual and preventive behaviors, contraception, knowledge of vector-borne diseases and their prevention, opinions and attitudes toward vaccination, and attitudes toward HBV, HCV, and HIV screening.
Operational flowchart, BaroTest Study, 2016. EIA: enzyme immunoassay; GP: general practitioner; HCV: hepatitis C virus.
Legend for flowchart in
Any participant in the 2016 Health Barometer aged 18 to 75 years, having medical health insurance, and not under guardianship was eligible for the BaroTest study.
Upon completion of the Barometer phone–based questionnaire, all those eligible for BaroTest were invited to receive a self-sampling kit for HBV, HCV, and HIV testing delivered by standard postal mail.
The collective and individual benefits of screening, as well as the overall objectives of the survey were explained. When a participant declined this invitation, the reason was recorded. If accepted, the investigator:
registered the first name and surname of the participant, along with the address to which the self-sampling kit would be sent;
informed the participant that personal information would be recorded separately from information collected during the phone questionnaire and would only be retained for the period covering the delivery of the self-sampling kit, home self-sampling, and the return of the sample to the laboratory for testing;
invited the participant to provide an email address and a telephone number so that a reminder could be sent in case the laboratory did not receive the dried blood sample card within 15 days of the dispatch date of the kit; and
provided the participant with a telephone number and an email to be used to contact the investigator, in case of nonreceipt of the kit, difficulties with its use, or for any other issues concerning the study.
An information letter outlining the objectives and details on voluntary participation in the BaroTest. This letter also listed the telephone numbers of various helplines (AIDS Info Service and Hepatitis Info Service) for any questions related to HIV or AIDS, hepatitis B virus (HBV), and hepatitis C virus (HCV)
A 2-page consent form to be signed and completed with the participant’s name, date of birth, postal address to receive the results of the tests, and the contact details of a general practitioner (GP) of his or her choice to whom the results would also be sent
The self-sampling kit, with detailed instructions for blood-sample collection; 2 single-use safety lancets; a prenumbered filter paper card (Whatman 903 FTA cards) with 5 preprinted circles zones, named spots (diameter: 6 mm); a disinfection cotton pad; and a small adhesive sensitive skin bandage
A sealable plastic bag to protect the dried blood spot (DBS) including a desiccant packet to remove any moisture from the DBS card
A bubble pouch for the 2 lancets to be returned with the DBS to ensure elimination of clinical infectious waste
A prestamped and preprinted rip-resistant envelope addressed to the National Reference Centre (NRC), the laboratory in charge of HIV, HCV, and HBV analyses
The BaroTest participant was randomly assigned a prenumbered self-sampling kit, thereby defining his or her identifier number in the study (BaroTest ID). The kit was sent inside a resealable cardboard box in a large and plain envelope within 3 days of the completion of the Barometer questionnaire (
After receiving the kit, the participant performed a capillary whole-blood sampling procedure by drawing blood from the fingertip with the lancet and depositing 1 large drop of free-flowing blood onto each of the 5 preprinted circles on the card, named
Once the self-sampling was performed and the blood sample card dried at room temperature (at least 3 hours), the participant inserted the DBS card into the sealable plastic bag with the desiccant packet, put the closed plastic bag into the resealable cardboard box along with the completed signed informed consent form and the bubble pouch with the 2 lancets, put the cardboard box in the return rip-resistant envelope, and sent it by mail to the National Reference Centre (NRC). Packaging and shipping followed international shipping guidelines and regulations for the Transport of Infectious Substances (WHO/HSE/GCR/2012.12).
The phone numbers of the HIV or AIDS and viral hepatitis national hotlines were mentioned in the consent form of the participants. These hotlines are open every day throughout the year. The staff was trained to address any sexual health question, including the topic of violence. The respondents were trained before the survey to answer any basic questions regarding the study. In addition, a study-specific email address was opened to the participants during the study to contact the study coordinator for any difficult question and to manage any adverse event that was transmitted via the hotlines.
Upon receipt of the envelope at the NRC, the following data were recorded in the NRC database: the BaroTest ID, the date of receipt, the name and address of the participant, the name and address of the general practitioner (GP), the status of the consent form (enclosed or not, signed or not, completed or not), and status of the DBS card (enclosed or not filled or unfilled). The DBS cards were assessed by a trained laboratory technician for both validity and amount of blood. The number of spots categorized as
Hepatitis B and C serological tests were based on the detection of the HBsAg and total anti-HCV antibodies, respectively. For this purpose, a single spot was eluted in 1 mL phosphate buffered saline with gentle agitation for 1 hour at 4°C and then centrifuged at 36,220
Qualitative HBsAg detection was performed by means of an automated enzyme immunoassay (EIA; VIDAS HBsAg Ultra, BioMerieux, France).
Detection of total anti-HCV was conducted by means of a third-generation EIA (aHCV Vitros ECi, Ortho-Clinical Diagnostics, Raritan, New Jersey, USA). If anti-HCV was positive, HCV RNA was detected with the Abbott RealTime HCV assay (Abbott Molecular, Des Plaines, Illinois), a real-time polymerase chain reaction–based method. Briefly, a second 6-mm spot was eluted into 1.5 mL Lysis buffer from Abbott at 56°C with gentle agitation for 30 min and then centrifuged at 36,220 g for 1 min before use.
For HIV analyses, a punch, 6 mm in diameter, from the DBS was placed in 150 µL of 0.01 M sodium phosphate buffer containing 10% bovine serum albumin and 0.05% Tween 20 (PBS-BSA-TW) and then incubated overnight at 4°C. The BioRad fourth-generation enzyme-linked immunosorbent assay (ELISA; Genscreen Ultra HIV Ag-Ab combo assay) was used to detect both anti-HIV and p24 antigen. The eluted samples were directly transferred to ELISA microplates (75 µL per well). Subsequent steps were performed according to the manufacturer’s recommendations.
If the HIV test proved positive, a confirmatory test (Western Blot, HIV Blot 2.2, or MP Diagnostics) was performed on the second spot. As described above, a punch 6 mm in diameter was placed in 1.4 mL of PBS-BSA-TW and then incubated overnight at 4°C. The eluted volume was brought up to a total of 2 mL with the addition of a dilution buffer from the Western Blot kit and incubated with the strip. Subsequent steps were performed according to the manufacturer’s recommendations.
All the results were validated by a medical biologist at the NRC and then recorded in the laboratory database.
The reporting procedure was explained in the participant consent form and differed according to the results (positive or negative). If all 3 tests for HIV, HBV, and HCV proved negative, the NRC informed the participant and the GP by postal mail. However, in this correspondence, it was also indicated that tests conducted using DBS do not have the same performance levels as conventional screening methods based on plasma or serum collected on venous puncture performed by specialists and, consequently, are not as accurate. Participants were advised that in case of recent exposure at risk of infection, they should contact their GP for additional biological testing, if required.
When at least one of the tests was positive or showed a limit result, the NRC sent the results of all tests to the GP of that participant only (ie, not to the participant) under confidential cover, along with a letter informing the GP that the participant had been invited to obtain the results and advising the GP to verify the positive result using a conventional standard screening method. The NRC contacted the participant by postal mail inviting him or her to contact the GP designated in the consent form to obtain the results of all tests.
Eight days after the self-sampling kit was posted to the participants, an email was automatically sent to those who had provided an email address, asking them to confirm reception or not. Those who did not receive the kit were invited to contact the survey institute for help and information.
The NRC sent a list of BaroTest identifier codes (reflecting individual participants) corresponding to the returned samples, twice a week to the survey institute by email. For each BaroTest ID listed, details were provided on what exactly had been received. In case of incomplete submissions (eg, no filter paper or no consent form) or missing information (eg, unsigned consent form or incomplete contact details), the survey institute telephoned the participant to enquire whether he or she required another sampling kit or consent form to be sent.
Participants were contacted by the survey institute if the DBS sample was not received by the NRC within 15 days after the self-sampling kit was sent. If the participant did not respond after 10 attempts, a voice message and email reminder (for those who had provided an email address) were sent. A second telephone reminder took place 10 days after the first one if no DBS reached the laboratory by that date. Similarly, a voice message was left after 10 attempts, and an email was sent if the person’s email address was available.
It was planned to include 15,000 people aged 15 to 75 years in the 2016 Health Barometer, approximately 14,000 of who were aged between 18 and 75 years.
The proportions of eligible individuals agreeing to participate in BaroTest and those who sent back the self-sampling kit were estimated on the basis of previous studies. In 2006, 76% of respondents in the French Sexual Behavior Survey agreed to receive a kit for the detection of Chlamydia trachomatis [
As the highest expected prevalence was for the HBsAg, estimated at 0.65% in 2004, 5000 persons would make it possible to estimate this prevalence with an accuracy of approximately 0.22%.
Acceptability of this screening protocol was based on the percentage of eligible individuals agreeing to receive the self-sampling kit (acceptance rate), on the proportion of people returning the DBS (return rate), and on the proportion of participants out of the total eligible population.
The feasibility of self-sampling testing was based on the number of participants with adequately filled blood spots and the number of participants with blood spots for which at least one virological analysis could be performed.
The amount of blood received was assessed by the number and size of the blood spots. Spots were classified into 3 categories: (1) correctly filled, (2) incorrectly filled, and (3) empty blood spots. In a
Prevalence was defined as the proportion of persons testing positive among the population tested. These data were extrapolated to the general population considering the BaroTest participation rate and characteristics of the participants.
The proportion of infected persons unaware of their infection was defined as the proportion of people who reported either that they had never been previously screened or that their last test was negative in the Barometer, among those testing positive.
All indicators were analyzed according to the characteristics of the participants collected in the Health Barometer questionnaire:
Sociodemographic characteristics: sex, age, country of birth, level of education, and employment status
Past at-risk exposure to HIV, HBV, and HCV infection: transfusion; drug use; tattooing or piercing performed without single-use equipment; surgical, dental, or nursing care; or prolonged stays in high endemic areas (eg, Africa, Asia, or the Middle East)
Awareness of hepatitis B and C and HIV serologic statuses: screening history and date and results of the last screening
The characteristics of those who refused to participate in the BaroTest and those who agreed to participate but did not return a biological sample were also analyzed.
The objectives and methods of the BaroTest study as well as the rights of participating individuals were presented both at the end of the telephone interview and in the letter of information sent with the self-sampling kit. At both times, the potential participant was informed that his or her participation was voluntary and that he or she was fully entitled to refuse participation with no prejudice of any kind. Moreover, mentioned in the letter of information was the right to object, to access, and to rectify participant information held electronically, in accordance with the provisions of Law Number 78-17, January 06, 1978 (French Data Protection Act).
Consent to participate in the BaroTest was obtained at 2 points:
Initial oral consent was obtained by telephone at the end of the Health Barometer interview after information was provided on the objectives of the study and guarantees given about of anonymity and confidentiality of the records.
Written consent was obtained via the consent form sent with the self-sampling kit. On this form, it was explained that completed informed consent was required to be able to participate in the BaroTest and to be informed of the results. The right of opposition to, access to, and rectification of all data collected relating to the BaroTest was explained. Participants were advised to contact the survey institute in charge of managing the personal data files if they wished to exercise this right. Participants were also informed that the NRC would store completed consent forms for 15 years and then destroy them.
In accordance with the French law, the reporting process was dependent on the results of the tests (positive or negative, see above). To optimize reporting, several reminder procedures were implemented to minimize the risk that participants would return envelopes with missing or incomplete contact addresses. When returned consent forms only included clear contact details for the GP, screening results were sent to him or her with an explanatory letter. The GP was then responsible for sharing the results with the participant.
For those who agreed to participate in the BaroTest, the survey institute was in charge of the recording of personal data at the end of the interviews as well as of sending the self-sampling kits and managing reminders.
To ensure the safety and confidentiality of personal data, a data file segregation procedure was implemented, whereby the matching of Health Barometer data (answers given during the phone questionnaire) with BaroTest data (testing results) was made impossible. Therefore, at no time did the survey institute receive or keep any of the results from the participants’ tests. The NRC was in charge of managing personal contact data for the participants to ensure delivery of their test results. No transfer of personal data took place between the NRC and other partners (the survey institute, Santé publique France). NRC only sent the ID list of the BaroTest kits it received to the survey institute to manage reminders.
At the end of the study, Santé publique France received the following:
From the survey institute: (1) an anonymized file of the answers to the Health Barometer 2016 questionnaire with Health Barometer identifiers and (2) a match list of BaroTest and Health Barometer IDs.
From the NRC: (1) a file containing the BaroTest IDs, (2) the corresponding testing results, and (3) the following information: quality of DBS, date of self-sampling, date of receipt of the self-sampling envelope, GP contact information, and date the results sent by the NRC. This file did not include any personal data. Santé publique France was therefore in possession of 3 anonymized files that it merged using the BaroTest and Health Barometer identifiers to obtain a single database. Following the generation of this database, the BaroTest IDs were definitively deleted.
Inclusion in BaroTest took place between January and July 2016. Following the reminder campaign and to account for late receipt of samples, it was decided that the NRC could analyze and report the results to the participants until December 31, 2016.