Skip to main content

Table 1 Study characteristics for studies reporting on benefit outcomes for screening versus no screening (key question 1)

From: Screening for chlamydia and/or gonorrhea in primary health care: systematic reviews on effectiveness and patient preferences

Author, year
Design, intensity, sample size, risk of bias Screening rates in intervention group (IG), rates of testing outside of study (IG; control group [CG]) Sex and age Baseline CT positivity of tested, all sexually active (Y/N) Recruitment Screening approach; CT vs CT and NG; location, test, and person testing; re-testing; co-interventions Outcome assessment
Incidence of PID in CG
Follow-up durations
Randomized controlled trials
 Andersen et al. 2011 [59]
1 screen offered
ROB: unclear (detection bias)
IG 9.0% vs CG 9.4% during 3 mos study period
21–24 yrs
7.1%; N Population-based via mailed kits Universal; CT; home-collected vaginal pipette, with NAAT; 70% re-tested; none PID: hospital discharge ICD codes or doxycycline prescriptions (only used for PID in Denmark; 33% by GPs). Incidence in CG 0.65%. Follow-up duration, 1 yr
EP and infertility: hospital discharge ICD codes. Follow-up duration, 9 yrs
 Garcia et al. 2012 [60]
RCT cluster
Screening offered every 8 wks over 3 yrs
20 cities with >50,000 inhabitants; follow-up survey using sampling at random sites at baseline (3732) and after 4 yrs (4156)
ROB: unclear (performance bias)
NR (interviewed FSWs 48,207 times during 20 8-wk cycles)
>14 yrs
Mean 24.5 yrs
15.5% CT, 2.4% NG; Y Outreach via mobile teams Universal; CT and NG (and other STIs); mobile site self-collected vaginal swabs with NAAT; re-testing NR but frequent visits; multi-faceted syndromic management in general population and clients of FSWs; condom promotion with motivational interviewing and free condoms; peer education Estimated population prevalence in FSWs using surveys (>99% of eligible enrolled) at random FSW sites. Follow-up duration, 3.5 yrs
 Hocking et al. 2018 [8]
Rural Australia
RCT cluster
3 annual screens offered
52 clusters (130 clinics of >500 16–29 yr olds)
ROB: unclear (performance and attrition biases)
24% ≥1 times over 3 yrs (8.2% pre-trial yr to 20% at 25–36 mos)
IG NR; CG rates increased from 8.2% pre-trial to 12.9% (stable over trial)
F and M
16–29 yrs
10% in those testing; 4.8% (4.5% females and 5.5% males) in prevalence surveys; Y Primary care (clinic attenders) Opportunistic; CT; in-clinic patient-collected vaginal or urine with NAAT; approx. 25% re-testing each year; multi-faceted with provider reminders, incentives, education, payments and feedback, and patient recall systems Clinic PID: cumulative incidence in clinics for women 16–33 with at least one clinic visit during intervention period. Criteria provided to all providers but not blinded. Incidence in CG 0.4%.
Hospital PID: ICD codes for all 15–34 yr olds living in each cluster. Incidence in CG 0.4%. Not used for main analysis because of low ascertainment and difference in trial and hospitalized populations
Estimated population prevalence (in clinic attenders): Using surveys of consecutive clinic attenders (70% response) before randomization and at end of trial (difference in change from baseline)
Follow-up duration for all outcomes: 3 yrs
 Hodgins et al. 2002 [12]
Nunavik region in Northern Quebec
RCT cluster
1 screen offered
12 communities in Nunavut (2320, 15–39 years)
ROB: high (incomplete outcome data with reported rates based on low uptake; multiple unclear domains)
F and M
All; focus on 15–39 yrs
7%; Y Outreach via community Universal CT; home urine sampling with PCR; re-testing NR; intensive community health education program Estimated population prevalence via reported rates over past yr in communities.
Follow-up duration, 1 yr
 Klovstad et al. 2013 [98]
1 screen offered
41,519 (10,000 IG)
ROB: low
IG 14% (85% of 16.5% testing via study or healthcare system)
IG 2.5%, CG 3.4%
F and M
18–25 yrs
IG 6.3% vs 11.6%; N Population-based register via mailed invitations with screening kits (no reminders) Universal; CT; home urine sampling via mailed kit via NAAT; N; N Treatment for CT: national prescription database (filled at least one prescription for (azithromycin, doxycycline, erythromycin, lymecyklin, amoxicillin) within 30 days following a positive test result. Follow-up duration, 3 mos
 Oakeshott et al. 2010 [28]
London, UK
1 screen
ROB: low
22% both groups (43% of those CT+ in CG)
16–27 (mean 21) yrs
5.4%; Y Outreach at common rooms, lecture theaters, and student bars at universities and further education colleges in London Universal; CT; outreach site self-collected vaginal swabs with NAAT; re-testing NR; informed of risks of CT infection PID: Any report by participants or their providers about signs and symptoms or dx, looked to medical records in general practitioners, hospitals, family planning clinics, and genitourinary medicine clinics. Used criteria for all cases, but medical records sometimes incomplete. Incidence in CG 1.8%.
Follow-up duration, 1 yr
 Ostergaard et al. 2000 [105]
RCT cluster
1 screen
17 schools (IG 928 vs CG 833)
ROB: high (attrition [>50%] and lack of cluster analysis), unclear for other domains except allocation concealment
IG 93% vs CG 7.5%
IG 29% and CG 36% (p=0.04)
≥15 yrs in high school (9% ≥19 yrs)
IG 5% vs CG 7.9%; Y Outreach in schools with provision of home kits or invitation/reminder to go to general practitioner or STI clinics Universal; CT; home sampling using vaginal pipette and NAAT vs. in-clinic swab with EIA; re-testing NR; information about consequences PID: Self-reported at follow-up questionnaire, with confirmation in registration for prescriptions. Incidence in CG 4.1%. Follow-up duration, 1 yr
 Scholes et al. 1996 [108]
Washington, USA
1 screen offered to selected females
ROB: unclear (selection, performance and detection biases)
18–34 yrs; 81% ≤24 yrs
7%; Y Primary care using telephone recruitment with questionnaire for high-risk considering race, douching, and ≥2 sexual partners in the preceding 12 months; married women excluded Universal; CT; in-clinic; clinician-collected cervical swabs (EIA or culture); re-testing NR; none PID: Self-report signs, symptoms, dx; medical records, hospital discharge, and pharmacy records. Dx had to be recorded and considered “clinical” (37 of 142 reported PID confirmed) but no specific criteria provided. Incidence in CG 2%. Follow-up duration, 1 yr
 Senok et al. 2005 [109]
RCT postal and opportunistic vs usual care over 4-month period
ROB: high for attrition bias; unclear for selection and detection
Opportunistic 21%; postal 48%; UC 0%; NR F
16–30 yrs; mean 24 yrs
Opportunistic 14%
Postal 5%
Usual care NR; N
Letters from general practice lists Universal opportunistic and postal; CT; NR; no; incentives to providers at practices Treatment for CT: clinic records. Follow-up duration, 4 mos
 van den Broek et al. 2012 [9]
RCT stepped-wedged cluster
3 annual offered
190 clusters with 317,304 people in three regions
ROB: unclear for performance and detection biases and incomplete outcome data (prevalence); high for incomplete outcome data (positivity)
16% (1st round), 10% (3rd round) (vs 13% in controls)
F and M
16–29 yrs
4.3% (7.1% in <20 yr olds); NR Population-based with postal invite to request sampling kit via internet Universal; CT; home with urine for males and vaginal swab or urine for females; kits for re-testing sent 6 mos after CT+ (uptake NR); none Estimated population prevalence using data from positivity with extrapolation to sexually active population of same ages in communities.
Follow-up duration, 2 yrs
Controlled clinical trials
 Clark et al. 2001 [88]
USA (Army recruits to South Carolina)
1 screen
ROB: high (selection and detection bias)
17-39 yrs;
88% ≤25yrs
9.1%; N (93% of IG but higher and unknown for CG) Community outreach via non-health Army training examination center Universal; CT; on-site self-collected urine with NAAT; re-testing NR; education on STDs PID, EP, infertility: Hospital discharge records. Incidence in CG 5.1/1000 PY (0.8%), 1.9/1000 PY and <0.01/1000 PY. Follow-up duration: mean 1.5 yrs
 Cohen et al. 1999 [89]
Louisiana, USA
Bi-annual screening offered over 2.5 years (CG invited in 3rd year with 1 test period)
5907 from 3 IG and 5 CG schools
ROB: high for selection, performance (11–53% testing outside of trial), attrition and other (no cluster adjustment) biases
83% at least once; annually, 52 to 65%
IG and CG 11% grade 9 and 53% grade 12, males ~20%
F and M
Grades 9–12
CT 11.5% females (8.7% in grade 9s vs 14% in grade 12s), 6.2% males
NG 2.5% females, 1.2% males (similar across ages)
Community health in high school health centers Universal; CT and NG; on-site urine with NAAT; re-testing NR but bi-annual testing; information about risks and consequences CT positivity in screening eligible students, who participated in screening, in IG after year 2 (5 tests offered) and CG (offered screening after year 2 in IG); Follow-up duration, 2.5 yrs
NG positivity in screening eligible students, who participated in screening, in IG after year 1 (3 tests offered) and CG (offered screening after 1 year of NG testing added in 2nd year of study). Follow-up duration, 1.5 yrs
Observational studies
 Sufrin et al. 2012 [111]
California, USA
Retrospective cohort
1 screen
ROB: moderate (selection bias with some adjustment)
14–49 yrs; mean 32 yrs (non-screened 7 yrs older)
NR; Y Primary care Unknown but assume some form of risk assessment for screening same day or up to 1 year before IUD insertion; CT; in-clinic but unknown test and methods; re-testing NR; none PID after IUD insertion: Health Maintenance Organization database ICD plus antibiotic pharmacy dispensed, with record review in 10% random sample if discordant; closed system. No specific criteria. Incidence in CG 0.36%. Follow-up duration, 3–15 mos (3 mos after IUD insertion but up to 15 mos from screen)
 Low et al. 2006 [101]
Retrospective cohort
48% screened once, 22% twice, 30% ≥3 tests over 10 yr
ROB: moderate (selection bias with some adjustment)
15–24 yrs
NR (11.5% at some time during follow-up); N Population-based Opportunistic used in county; CT; in-clinic sampling NR with culture; none PID, EP, infertility: hospital discharge in-(all yrs) and out-(last 6 yrs) patient. No criteria. Incidence in CG 2.9%, 1.9%, 3.1% over 10 yrs. Follow-up duration, 10 yrs
  1. Abbreviations: CCT controlled clinical trial, CG control group, CT Chlamydia trachomatis, Dx diagnosis, F females, FSW female sex workers, ICD International Classification of Diseases, IG intervention group, IUD intrauterine device, M males, mos months, NAAT nucleic acid amplification test, NG Neisseria gonorrhoeae, NR not reported, PID pelvic inflammatory disease, RCT randomized controlled trial, ROB risk of bias, wks weeks, yrs years