Enzyme Immunoassay

The TS study was the 37th semiannual cross-section of the Urban Health Study (UHS), a study of IDUs in San Francisco. Watters and Biernacki,9 (link) the developers of TS, first implemented the method in the first UHS cross-section in 1986. The procedures and results from this study have been published extensively over the past two decades.29 (link)–31 (link) Briefly, the five steps involved in developing and refining the TS plan are as follows: (1) Collect indicator data from sources including drug treatment admissions data, IDU HIV/AIDS case data from the San Francisco Department of Public Health (SFDPH), data from Citywide HIV testing sites, and narcotics arrest data from the San Francisco police departments. (2) Collect ethnographic data through block-by-block “walk-throughs,” which were conducted at different times of day and night. Ethnographic data collection also included discussions with key informants regarding their observations on the prevalence and type of drug use in various communities. (3) Develop TS plan by estimating the size and demographic characteristics of the IDU population in each area and set recruitment targets. (4) Conduct outreach to recruit IDUs to community field sites in the neighborhoods with the highest concentration of IDUs per secondary data (marked by stars in Fig. 1b). (5) Refine and revise targeted sample after monthly assessments of how well the recruitment targets were met.
Figure 1

Distribution of study recruits by zip code. a RDS. b Targeted sampling.

Eligibility criteria included the following: (1) reported injecting illicit drugs within the past 30 days, (2) had visible sign of injection (“tracks”), (3) were at least 18 years of age at the time of interview, and (4) were able to speak English or Spanish. Participants from previous serial cross-sections did not receive any special recruitment contact, but they were automatically eligible for future cross-sections (6 months apart), even if they had switched to noninjecting methods or had quit using drugs. Participants were assigned a unique ID code, and we checked their identification by asking five questions: sex, birth year, age, race/ethnicity, state of birth, and first two letters of mother's maiden name. This helped to determine which observations were duplicates. For this analysis, we only included active IDUs who reported injecting drugs in the previous 30 days.
After providing informed consent to this anonymous study, participants were interviewed in person by a trained interviewer in a private space using a structured questionnaire on a computer-assisted programmed interview (CAPI) using QDS software (QDS; NOVA Research Company, Bethesda, MD). They were paid $15 for contributing to the study. Questions covered demographic information, injecting and sexual risk behaviors, and utilization of health care, drug treatment, and HIV prevention programs. The questions pertained to the 6-month period preceding the interview date. Blood specimens were drawn following the interview to assess HIV status using enzyme immunoassay and Western blot assay, following standard laboratory methods. Participants were asked to return for HIV serology results in 2 weeks. They were offered HIV counseling, provided with referrals to medical and social services, and paid $15. Study protocols were approved by the University of California, San Francisco (UCSF) Committee on Human Research.

In all centres, patients undergoing FMT treatment were registered prospectively. Data about IBD outcome and long-term follow-up were in part collected retrospectively (Supplemental Figure 1).
Data collection was performed by each centre using files of the FMT services and hospital records for the patients. If possible, patients were contacted directly. The following baseline characteristics were collected: age, gender, and the use of PPIs. The following data about the CDI were collected: number of episodes; diagnostics by polymerase chain reaction or toxin enzyme immunoassay; and information about previous treatment with metronidazole, vancomycin, fidaxomicin, or bezlotoxumab. Severe CDI was defined as leukocytes ⩾15 × 10⁹/L and/or a 50% increase in creatinine at baseline.^{17 (link)} FMT data included the pre-treatment regimen (antibiotics, bowel lavage), total number of FMTs needed per patient, the route of administration of FMT, and the total amount of faeces (grams) used for preparation of the suspensions or capsules that were administered per patient. Data about clinical recurrence and microbiological testing for CDI after FMT were collected at 8–12 weeks after FMT. Long-term follow-up data of CDI recurrence were included if available.
For IBD, information was collected about the diagnosis according to the Montreal classification and the disease duration. Previous and current IBD medication at the moment of FMT and the use of immunosuppressive medication (including corticosteroids and budesonide, immunomodulators and biologicals) was assessed. Both at baseline and 8 weeks after FMT, the presence of an IBD flare was based on information from the treating physician and/or endoscopic scores. In case of a concomitant flare, remission-induction therapy was defined as the use of prednisolone or budesonide at the moment of FMT, or recently initiated antitumor necrosis factor (TNF) treatment (⩽2 months before FMT). Also haemoglobin (mmol/l) and C-reactive protein (mg/l) in the blood and the calprotectin (µg/g) in the faeces were collected at baseline and after 8 weeks.
The long-term follow-up period per patient was calculated from the date of FMT up to 31 December 2020. Long-term follow-up data included information about possibly occurring events and if yes, the number of days after FMT it occurred. Possible occurring events, collected via patient recall or from hospital records, were as follows: a recurrence of CDI, the development of an IBD flare, general infection and antibiotic use, hospital admission, colectomy, and occurrence of death.