Purpose: This study was conducted to determine the prevalence and risk factors for keratoconus worldwide. Methods: In this meta-analysis, using a structured search strategy from 2 sources, 4 electronic databases (PubMed, Web of Science, Google Scholar, and Scopus) and the reference lists of the selected articles were searched from inception to June 2018 with no restrictions and filters. The outcome of the study was the prevalence of keratoconus and its risk factors, including eye rubbing, family history of keratoconus, atopy, allergy, asthma, eczema, diabetes type I and type II, and sex. Results: In this study, 3996 articles were retrieved, of which 29 were analyzed. These 29 articles included 7,158,241 participants from 15 countries. The prevalence of keratoconus in the whole population was 1.38 per 1000 population [95% confidence interval (CI): 1.14–1.62 per 1000]. The prevalence of keratoconus was 20.6 per 1000 (95% CI: 11.68–28.44 per 1000) in men and 18.33 per 1000 (95% CI: 8.66–28.00 per 1000) in women in studies reporting sex. The odds ratio of eye rubbing, family history of keratoconus, allergy, asthma, and eczema was 3.09 (95% CI: 2.17–4.00), 6.42 (95% CI: 2.59–10.24), 1.42 (95% CI: 1.06–1.79), 1.94 (95% CI: 1.30–2.58), and 2.95 (95% CI: 1.30–4.59), respectively. Conclusions: The results of this study, as the most comprehensive meta-analysis of keratoconus prevalence and risk factors, showed that keratoconus had a low prevalence in the world and eye rubbing, family history of keratoconus, allergy, asthma, and eczema were the most important risk factors for keratoconus according to the available evidence.

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Nowadays there is an ongoing acute respiratory outbreak caused by the novel highly contagious coronavirus (COVID-19). The diagnostic protocol is based on quantitative reverse-transcription polymerase chain reaction (RT-PCR) and chests CT scan, with uncertain accuracy. This meta-analysis study determines the diagnostic value of an initial chest CT scan in patients with COVID-19 infection in comparison with RT-PCR. Three main databases; PubMed (MEDLINE), Scopus, and EMBASE were systematically searched for all published literature from January 1st, 2019, to the 21st May 2020 with the keywords "COVID19 virus", "2019 novel coronavirus", "Wuhan coronavirus", "2019-nCoV", "X-Ray Computed Tomography", "Polymerase Chain Reaction", "Reverse Transcriptase PCR", and "PCR Reverse Transcriptase". All relevant case-series, cross-sectional, and cohort studies were selected. Data extraction and analysis were performed using STATA v.14.0SE (College Station, TX, USA) and RevMan 5. Among 1022 articles, 60 studies were eligible for totalizing 5744 patients. The overall sensitivity, specificity, positive predictive value, and negative predictive value of chest CT scan compared to RT-PCR were 87% (95% CI 85–90%), 46% (95% CI 29–63%), 69% (95% CI 56–72%), and 89% (95% CI 82–96%), respectively. It is important to rely on the repeated RT-PCR three times to give 99% accuracy, especially in negative samples. Regarding the overall diagnostic sensitivity of 87% for chest CT, the RT-PCR testing is essential and should be repeated to escape misdiagnosis.

There remains a need to better understand the prognostic factors affecting the long-term survival in patients with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS), particularly in developing countries. We extracted data from 585 patients' medical records available at the triangular clinics for behavioural diseases. The outcomes of interest were the survival rates of progression to AIDS and death in HIV-positive subjects. The effect of several prognostic factors on survival time was investigated. One-year, five-year and 10-year survival rates from time of HIV diagnosis to AIDS were 89%, 69% and 30%, respectively. One-year and five-year survival rates from AIDS to death were 76% and 46%, respectively. One-year, five-year and 10-year survival rate from HIV diagnosis to death were 87%, 67% and 40%, respectively. Hazard ratio of progression to AIDS in HIV-positive subjects who were co-infected with tuberculosis was 4.50 (p < 0.001). Hazard ratio of death from AIDS-related causes was 4.77 in patients who did not receive highly active antiretroviral therapy compared to those who did (p < 0.001). Co-infection with tuberculosis was one of the most important prognostic factors of progression to AIDS and antiretroviral treatment was found to be an effective measure in suppressing HIV viral replication and improving the survival of patients living with HIV.

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