Latest Research on Epidemiology : Dec 2021

Epidemiology: principles and methods

The influence of the earlier work is of course apparent, but the change in emphasis from methods to principles is so great that it is probably better to regard the present book as a new text.

Although many of the classical illustrations (such as Snow and Goldberger) are used, the main con-cern is with the aetiology of chronic disease. This is approached through discussions of the nature of epidemiology, and of what makes an association one of cause and effect. These are followed by a review of the application of scientific method to epidemiology. After digressions into the bases of disease classification and measurement (incidence, prevalence, and the like) there is a chapter on the sources of data that are routinely available in various countries-vital records, disease registers, morbidity surveys, record linkage schemes-and a note on the methods by which individuals may be traced. The succeeding chapters discuss aetiology in terms of person, place, and time, and of their interactions (migration, birth cohort analysis, space-time clustering). Later chapters describe the principles of longitudinal observational studies, of case-control studies, and of preventive trials. The last chapter, ” Genetics and Epidemiology “, deals with some widely differing subjects-for example twin studies and studies of the effects of maternal age. [1]

TFOS DEWS II Epidemiology Report

The subcommittee reviewed the prevalence, incidence, risk factors, natural history, morbidity and questionnaires reported in epidemiological studies of dry eye disease (DED). A meta-analysis of published prevalence data estimated the impact of age and sex. Global mapping of prevalence was undertaken. The prevalence of DED ranged from 5 to 50%. The prevalence of signs was higher and more variable than symptoms. There were limited prevalence studies in youth and in populations south of the equator. The meta-analysis confirmed that prevalence increases with age, however signs showed a greater increase per decade than symptoms. Women have a higher prevalence of DED than men, although differences become significant only with age. Risk factors were categorized as modifiable/non-modifiable, and as consistent, probable or inconclusive. Asian ethnicity was a mostly consistent risk factor. The economic burden and impact of DED on vision, quality of life, work productivity, psychological and physical impact of pain, are considerable, particularly costs due to reduced work productivity. Questionnaires used to evaluate DED vary in their utility. Future research should establish the prevalence of disease of varying severity, the incidence in different populations and potential risk factors such as youth and digital device usage. Geospatial mapping might elucidate the impact of climate, environment and socioeconomic factors. Given the limited study of the natural history of treated and untreated DED, this remains an important area for future research.[2]

Epidemiology of IBS

Irritable bowel syndrome (IBS) is a common functional gastrointestinal (GI) disorder. Because not everyone needs to seek care, population-based studies are needed to truly understand the epidemiology of IBS. About 10% of the population has IBS at any one time and about 200 people per 100,000 will receive an initial diagnosis of IBS over the course of a year. IBS patients are more frequently younger in age, and a female predominance has been observed in Western countries and tertiary care settings. IBS patients commonly report overlapping upper GI, as well as a variety of non-GI, complaints. [3]

Epidemiology of Low Back Pain in Saudi Arabia

Background: Low Back Pain (LBP) is a common disorder involving the muscles and bones of the back. The patients ranged in age from 15 to 52 years. The condition may be further categorized by the underlying etiology as either mechanical, non-mechanical, or referred pain. Little is known about the epidemiology of this condition in the Saudi Arabia.

Aim: To review epidemiology of LBP in the Saudi Arabia.

Methods: A computer-based literature search was conducted using relevant keywords to retrieve studies conducted in Saudi Arabia relating to LBP. Fifteen articles were identified initially. After screening for exclusion criteria and retrieving full texts, a total of Twelve articles was used for this study.

Results: Seven studies were cross-sectional and found a prevalence and pattern ranging from 53.2% to 79.17%. Studies about risk factors/prognostic markers were conducted in clinical-settings; using a case-control design mostly (n=4) and Cohort study (n=1). Vitamin D deficiency, to determine the correlation between the vitamin deficiency and pain.

Conclusion: Low Back Pain has multifactorial risks, etiology and increased incidence and prevalence.

Recommendation: Future studies in the Saudi Arabia should focus upon surveying the extent of LBP, identifying various cultural risk factors and utilization of LBP markers in diagnostic and prognostic enforcement.[4]

Epidemiology of Hepatitis C Virus Infection in Egypt

Hepatitis C virus constitutes an epidemic in Egypt having the highest prevalence in the world of 14.7%. The reasons behind this unique epidemic may be dated back to iatrogenic role of parenteral antischistosomal therapy campaigns to control endemic schistosomiasis. Other routes of infection are contributing to the ongoing HCV transmission. The prevalent genotype in Egypt is type 4 (73%), the origin, evolution, and dynamics are difï¬cult to determine. Risk factors for acquiring HCV infection include: History of antischistosomal injection treatment before 1986, old age, male gender, and residence in rural areas. Other risk factors include; injection therapy, blood transfusion prior to 1994, exposure to various facility-based medical procedures, and occupational transmission among health care workers. In community settings, a set of risk factors, mostly related to prevailing social and cultural conditions, are responsible for maintaining the high rates of HCV transmission. Chronic HCV is the main cause of liver cirrhosis and liver cancer in Egypt and, indeed, one of the top five leading causes of death. It kills an estimated 40,000 Egyptians a year.

When talking about children, current HCV seroprevalenceis high, approximately 5-8%. It is to be emphasized that HCV infection is not always benign in the childhood period in Egypt. It has been shown that blood transfusion, surgical procedures, dental treatment, male circumcision and age above 10 years are important risk factors associated with anti-HCV antibody prevalence. In addition, vertical transmissions, and household transmission have been documented as routes of transmission. Occult HCV infection is defined as elevated liver function tests and negative HCV antibodies in serum, while HCV RNA is detectable in liver tissue and peripheral polymorphonuclear cells (PBMCs). Interest in occult HCV has emerged recently in Egypt. Studies at a national level are being carried out, but no results have yet been released. Many small scale studies have been performed among particular patient groups, which have highlighted the importance of this disease entity. [5]


[1] MacMahon, B. and Pugh, T.F., 1970. Epidemiology: principles and methods. Epidemiology: principles and methods.

[2] Stapleton, F., Alves, M., Bunya, V.Y., Jalbert, I., Lekhanont, K., Malet, F., Na, K.S., Schaumberg, D., Uchino, M., Vehof, J. and Viso, E., 2017. Tfos dews ii epidemiology report. The ocular surface, 15(3), pp.334-365.

[3] Choung, R.S. and Locke 3rd, G.R., 2011. Epidemiology of IBS. Gastroenterology Clinics of North America, 40(1), pp.1-10.

[4] Awaji, M.A., 2016. Epidemiology of low back pain in Saudi Arabia. Journal of Advances in Medical and Pharmaceutical Sciences, pp.1-9.

[5] Amer, F.A., Gohar, M. and Yousef, M., 2015. Epidemiology of hepatitis C virus infection in Egypt. International Journal of Tropical Disease & Health, pp.119-131.

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