This was a cross-sectional study that collected multi-country data using an online survey. The study was approved by the Research Ethics Committee of the Faculty of Dentistry, Alexandria University, Egypt (IRB 00010556)-(IORG 0008839)/6-11-2016), with further approvals from the University of Giessen in Germany, Bosnia and Herzegovina, (B&H), Indonesia, Iran, Jordan, Saudi Arabia, and Serbia. We included dental academics or educators working in dental academic institutions. Dental students (undergraduate and postgraduate) and dentists who do not work in dental educational institutions were excluded.
Table 1 lists the countries included in the study. The number of dental academics per country was estimated by using a ratio of 1:5 dental academics to dentists, based on information extracted from the World Health Organization’s (WHO) Global Health Observatory database (15). The required number per country to achieve statistical power was calculated, assuming 95% confidence level, 5% margin of error, and 71% adherence to infection control practices among dental academics (16).
Table 1
Countries included in the study, the number of recruited dental academics, and response rate, March-April 2020.
Countries | Number of recruited academics | Number of responses | Response rate |
Bosnia and Herzegovina | 98 | 58 | 59.2 |
Brazil | 1350 | 118 | 8.7 |
Egypt | 310 | 126 | 40.6 |
France | 630 | 44 | 7.0 |
Germany | 1400 | 234 | 16.7 |
India | 1662 | 240 | 14.4 |
Indonesia | 200 | 178 | 89 |
Iran | 700 | 274 | 39.1 |
Italy | 527 | 62 | 11.8 |
Japan | 205 | 6 | 2.9 |
Jordan | 100 | 75 | 75.0 |
Kenya | 60 | 4 | 6.7 |
Korea | 220 | 36 | 16.4 |
Libya | 103 | 32 | 31.1 |
Myanmar | 100 | 28 | 28.0 |
Nigeria | 86 | 45 | 52.3 |
Palestine | 53 | 27 | 50.9 |
Peru | 150 | 15 | 10.0 |
Saudi Arabia | 90 | 55 | 61.1 |
Serbia | 400 | 11 | 2.8 |
Syria | 150 | 17 | 11.3 |
Thailand | 470 | 27 | 5.7 |
United Arab Emirates | 77 | 14 | 18.2 |
United Kingdom | 150 | 63 | 42.0 |
United States | 6820 | 175 | 2.6 |
Yemen | 200 | 81 | 40.5 |
Total = 26 | 14,281 | 2,045 | 14.3 |
We reached the convenience sample of participants with the use of two strategies. First, we asked collaborators to distribute the survey to dental academics in their respective countries. Second, we scanned the official institutional websites of dental schools in countries where we had no collaborators (USA and Brazil) to collect faculty email addresses and directly invited them to take part in the survey. We aimed to include academics from as many institutions per country as possible.
The online survey invitation included an introduction of the study team; the estimated time required to complete the survey; information about the right to withdraw from the survey; and details about confidential handling of the survey information. The survey was open from March 15th to April 27th, 2020.
The survey included two sections of close-ended questions. The first section assessed knowledge based on information from the WHO and the Centers for Disease Control and Prevention (CDC) official websites posted during March 2020 about COVID-19 (12, 16–18). We used questions with multiple selections of items about aspects of COVID-19 infection. Six items addressed the mode of transmission; 4 items addressed major warning symptoms; 5 items addressed treatment and management; 4 items addressed diagnosis; 5 items addressed protection, and 5 items addressed precautions during dental treatment. The score for each domain was the sum of the correct responses, with domain scores ranging from zero to a maximum of 6, 4, 5, 4, 5, and 5, respectively. The total knowledge score was the sum of all domains, ranging from zero to 29. The second section had 12 questions concerning the dentists’ background: age; sex; living arrangements; country of practice; specialization; highest academic degree obtained; number of years in academia; number of courses taught/coordinated; average number of students per semester; average number of patients attended to in the clinic per day; training on the handling of public health emergencies; and administrative role. Appendix 1 includes details of the questionnaire.
In a pilot study, five dental academics tested the content and face validity of the questionnaire and the time taken to respond to the questionnaire (average, 4.36 minutes). The results of this pilot study were not included in the final analysis.
Using Survey Monkey®, an online survey platform, we prepared the links to the survey with settings to ensure that it would be anonymous, that participants could change their answers freely before they choose to submit, and that it was not time-limited. One submission per electronic device was allowed. We created the questionnaire in English and translated it when needed to the language of dental academia, such as in Brazil and Iran. The translation was done by native dentists with back translation to English to ensure accuracy. We sent out links to eligible participants through email or social media groups of academics only and offered no incentives or rewards. The first invitation to participate covered the period from March 15th to 27th 2020, and follow-up reminders covered the period from April 8th to 14th (19).
We calculated the percentages of correct responses and plotted them as bar graphs. We assessed the internal consistency with Kuder-Richardson formula 20 (K-R 20), a modification of Cronbach’s alpha (20). We compared the domain percentage scores using multivariate analysis of variance (MANOVA), controlling for country effect. We used the linear mixed-model procedure in SPSS version 23.0 to construct unadjusted multilevel linear regression models, where we entered the explanatory variables one at a time. The outcome variable was the total knowledge score. The explanatory variables were at the individual level (background information) and country-level (the number of COVID-19 cases per million population obtained from Worldometer website) (2). We developed an unconditional model, including no explanatory variables, to calculate the baseline variance due to random differences among countries. In the second step, we entered individual and country-level variables that were significantly associated with the outcome variable in the unadjusted models into a multilevel model as fixed effects and used country as a random effect. We calculated regression coefficients (B), 95% confidence intervals (CIs), residual variance, deviance (as -2 log-likelihood (LL)), X2 test to assess improvement in the goodness of fit relative to the unconditional model and increase in pseudo R2 (21).