Table 1.
Baseline characteristics of reviewed documents (N = 45)
| Characteristic | Frequency (%) |
|---|---|
| General characteristics | |
| Authors’ affiliation | |
| Academic institution | 22 (48.89) |
| Academic and government | 7 (15.56) |
| Academic and hospital | 1 (2.22) |
| Academic and International NGO | 1 (2.22) |
| Governmental health institution | 12 (26.67) |
| Governmental health institution and International NGO | 1 (2.22) |
| International NGO | 1 (2.22) |
| Document type | |
| Conference proceeding | 5 (11.11) |
| Peer-reviewed journal | 40 (88.89) |
| Publication period | |
| < 1990 | 4 (8.89) |
| 1990–2000 | 6 (13.33) |
| 2001–2010 | 6 (13.33) |
| 2011–2018 | 29 (64.44) |
| State where study was undertaken | |
| Akwa-Ibom and Cross-River | 1 (2.22) |
| Bauchi | 1 (2.22) |
| Bauchi and Gombe | 1 (2.22) |
| Bauchi, Borno and Gombe | 2 (4.44) |
| Bauchi, Borno and Osun | 1 (2.22) |
| Benue | 1 (2.22) |
| Borno | 2 (4.44) |
| Cross-River | 4 (8.89) |
| Jigawa | 2 (4.44) |
| Kaduna | 4 (8.89) |
| Kano | 2 (4.44) |
| Katsina | 1 (2.22) |
| Lagos | 2 (4.44) |
| Nasarawa | 1 (2.22) |
| Niger | 1 (2.22) |
| Ogun | 1 (2.22) |
| Osun | 2 (4.44) |
| Oyo | 7 (15.56) |
| Rivers | 1 (2.22) |
| Multiple states (> 3 states) | 8 (17.78) |
| Study context | |
| Epidemic | 29 (64.44) |
| Endemic | 9 (20.00) |
| Endemic and epidemic | 6 (13.33) |
| Unspecified | 1 (2.22) |
| Study approach | |
| Prospective | 18 (40.00) |
| Retrospective | 23 (51.11) |
| Prospective and retrospective | 3 (6.67) |
| Unclear | 1 (2.22) |
| Study design | |
| Case-control | 10 (22.22) |
| Cross-sectional | 28 (62.22) |
| Review | 4 (8.89) |
| Unspecified | 3 (6.67) |
| Median sample size reported in documents (IQR)a | 329 (109–1220) |
| Age group of study participants | |
| All age groups | 17 (37.78) |
| Adults | 2 (4.44) |
| Children under-5 years | 1 (2.22) |
| Children under-14 years | 1 (2.22) |
| Unspecified | 24 (53.33) |
| Funding for study | |
| Unspecified | 41 (91.11) |
| Yes | 4 (8.89) |
| Ethical approval for the study | |
| Unspecified | 34 (75.56) |
| Yes | 11 (24.44) |
| Clinical characteristics | |
| Data collection approach | |
| Record extraction | 4 (8.89) |
| Microbiological examination | 7 (15.56) |
| Questionnaire | 9 (20.00) |
| Record extraction and microbiological examination | 1 (2.22) |
| Questionnaire and microbiological examination | 9 (20.00) |
| Record extraction and questionnaire | 2 (4.44) |
| Record extraction, questionnaire and microbiological examination | 1 (2.22) |
| Record extraction, questionnaire and observation | 2 (4.44) |
| Unspecified | 10 (22.22) |
| Report of case fatality rate (%) | |
| No | 23 (51.11) |
| Yes | 22 (48.89) |
| Mean (SD) case fatality rateb | 6.53 (3.90) |
| Report of attack rate | |
| No | 40 (88.89) |
| Yes | 5 (11.11) |
| Location of sample collection | |
| Community | 11 (24.44) |
| IDP camp | 1 (2.22) |
| Primary | 1 (2.22) |
| Secondary | 1 (2.22) |
| Tertiary | 4 (8.89) |
| Primary and secondary | 1 (2.22) |
| Secondary and tertiary | 3 (6.67) |
| Tertiary and private | 1 (2.22) |
| Unspecified health facility | 2 (4.44) |
| Unspecified health facility and community | 4 (8.89) |
| Unspecified health facility and IDP camp | 1 (2.22) |
| Unspecified | 15 (33.33) |
| Culture | |
| No | 11 (24.44) |
| Yes | 22 (48.89) |
| Unspecified | 12 (26.67) |
| Rapid diagnostic test performed | |
| No | 40 (88.89) |
| Yes | 5 (11.11) |
| Identified biotype | |
| Classical | 1 (2.22) |
| El-Tor | 4 (8.89) |
| Classical & El-Tor | 2 (4.44) |
| Atypical El-Tor | 1 (2.22) |
| Unspecified | 37 (82.22) |
| Identified serogroup | |
| O1 | 13 (28.89) |
| Non-O1 | 2 (4.44) |
| Unspecified | 30 (66.67) |
| Identified serotype | |
| Ogawa | 8 (17.78) |
| Inaba | 1 (2.22) |
| Ogawa and Inaba | 1 (2.22) |
| Unspecified | 35 (77.78) |
a Based on 34 out of 45 documents
bBased on 22 out of 45 documents