We agree with colleagues that in our first paper, some estimate measures of effect modification such as relative risk reduction (RRR), absolute risk reduction (ARR) and number needed to treat (NNT) with the intervention of hydroxychloroquine were not analyzed [1]. In addition, excluding six patients from our analysis may have biased our results.
For that reason, we reanalyzed our data about all 42 patients initially enrolled in our survey. Outcome of analysis was “contagiousness at day 7”. According to WHO criteria, patients were considered not contagious if they have two consecutive negative PCR results at least 24 hours apart [2]. Analysis was carried out using the STATA version 15.1 statistical package.
Table 1 shows the contingency table and the estimated effect measures. The incidence of the hydroxychloroquine (HCQ) exposed group was 0.5 and the incidence of the unexposed group was 0.1667. The treatment with HCQ increased by a factor of 2 the proportion of non-contagious patients at day 7 (relative risk (RR) = 1.80, 95%CI = [1.10 – 2.94], p = 0.0257). The RRR was 2.0, the ARR was 0.36, 95%CI = [0.08 – 0.63] and NNT was 2.81, 95%CI = [1.58 – 12.55]. HCQ and azithromycin (AZ) combined treatment increased by a factor of 4 the proportion of non-contagious patients at day 7 (RR = 3.75, 95%CI = [1.17 – 12.01], 0.0194. The RRR was 2.75, the ARR was 0.45, 95%CI = [0.08 – 0.84] and NNT was 2.18, 95%CI = [1.20 – 12.30].
Table 1.
Hydroxychloroquine and COVID-16 negative PCR
| Contagiousness at Day7 | |||
|---|---|---|---|
| Event (negative PCR) | No event (positive PCR) | ||
| Hydroxychloroquine versus control | |||
| Case (HCQ) | 12 | 12 | |
| Control | 3 | 15 | |
| Relative risk [95%CI], p-value | 1.80 [1.10 – 2.94], p = 0.0257 | ||
| Relative risk reduction | 2.0 | ||
| Absolute risk reduction [95%CI] | 0.36 [0.08 – 0.63] | ||
| Number needed to treat [95%CI] | 2.81 [1.58 – 12.55] | ||
| Hydroxychloroquine and azithromycin combined treatment versus control | |||
| Case (HCQ + AZ) | 5 | 3 | |
| Control | 3 | 15 | |
| Relative risk [95%CI], p-value | 3.75 [1.17 – 12.01], 0.0194 | ||
| Relative risk reduction | 2.75 | ||
| Absolute risk reduction [95%CI] | 0.45 [0.08 – 0.84] | ||
| Number needed to treat [95%CI] | 2.18 [1.20 – 12.30] | ||
In conclusion, the reintegration of excluded patients in our analysis and the calculation of the estimate measures of effect modification confirm the effectiveness of the HCQ alone and of HCQ-AZ treatments on viral clearance of SARS-CoV-2 in COVID-19 patients.
Funding
No funding sources
Competing interest
The authors declare no competing interests.
Ethical approval
Not applicable
Footnotes
This article refers to 10.1016/j.ijantimicag.2020.105949 and 10.1016/j.ijantimicag.2020.106172.
References
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