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The introduction of antiretroviral therapy (ART) significantly decreases the incidence of tuberculosis (TB) in people living with human immunodeficiency virus (PLWHIV). However, a considerable proportion is still co-infected with TB after ART initiation. Thus, this study aimed to assess the effect of long-term HAART on the incidence of TB among PLWHIV in Addis Ababa, Ethiopia. A matched nested case-control study was conducted among PLWHIV who were enrolled in ART clinics in Addis Ababa, Ethiopia from 2013 up to 2018. Cases were HIV-TB co-infected individuals who were taking antiretroviral treatment, while controls were PLWHIV without TB who were taking antiretroviral treatment. The cases and controls are matched exactly in age and sex. Data were entered in Epi Info version 7.1 and analyzed using SPSS version 20. Bi-variable and multivariable conditional logistic regression were employed along with 95% CI. A P-value <0.05 in the multivariable analysis was considered statistically significant. Fifty-seven cases were compared with 114 controls. Accordingly, previous TB history (X ; 13.790, < 0.001), baseline functional status (X ; 9.120, = 0.010), baseline WHO clinical stage (X ; 10.083, = 0.001), baseline hemoglobin value (X ; 6.985, = 0.008), baseline body mass index (X ; 3.873, = 0.049), isoniazid preventive treatment (X ; 8.047, = 0.005), baseline CD4 value (X ; 12.741, < 0.001) and length of stay on ART (X ; 53.359, < 0.001) were associated with developing TB. Length of stay on ART was found to be the statistically significant determinant of TB infection after ART initiation (aOR = 5.925, 95% CI = 2.649-13.250). Advanced clinical stages at the baseline, previous TB history, and not taking IPT were associated with TB infection. The long-term ART exposure significantly decreases tuberculosis incidence in PLWHIV. Thus, retaining PLWHIV on ART would be important to decrease the incidence of TB in this group of individuals.

Background Breast cancer is an umbrella term referring to a group of biologically and molecularly heterogeneous diseases originating from the breast. Globally, incidences of breast cancer has been increasing dramatically over the past decades. Analyses of multiple clinical “big data” can aid us in clarifying the means of preventing the disease. In addition, predisposing risk factors will be the most important issues if we can confirm their relevance. This study aims to provide an overview of the predisposing factors that contribute to a higher possibility of developing breast cancer and emphasize the signs that we ought to pay more attention to. Methods This is a matched nested case-control study. The cohort focused on identifying the eligible risk factors in breast cancer development by data screening (2000-2013) from the Taiwan National Health Insurance Research Database (NHIRD) under approved protocol. A total of 486,069 females were enrolled from a nationwide sampled database, and 3281 females was elligible as breast cancer cohort, 478,574 females who had never diagnosed with breast cancer from 2000 to 2013 were eligible as non-breast cancer controls, and matched to breast cancer cases according to age using a 1:6 ratio. Results We analyzed 3281 breast cancer cases and 19,686 non-breast cancer controls after an age-matched procedure. The significant predisposing factors associated with breast cancer development including obesity, hyperlipidemia, thyroid cancer and liver cancer. As for patients under the age of 55, gastric cancer does seem to have an impact on the development of breast cancer; compared with their counterparts over the age of 55, endometrial cancer appears to exhibit an evocative effect. Conclusions In this nationwide matched nested case-control study, we identified obesity, hyperlipidemia, previous cancers of the thyroid, stomach and liver as risk factors associated with breast cancer. However, the retrospective nature and limited case numbers of certain cancers still difficult to provide robust evidence. Further prospective studies are necessitated to corroborate this finding in order to nip the disease in the bud. Trial registration The studies involving human participants were reviewed and approved by the China Medical University Hospital [CMUH104-REC2-115(AR-4)].

SummaryWe investigated the association between bisphosphonate treatment and the risk of stroke using a large routine clinical dataset. We found no association between bisphosphonate treatment and risk of stroke, after adjusting for large number of clinical and demographic confounders.IntroductionThere is conflicting evidence on the link between bisphosphonates and stroke with studies variously showing increased, decreased or unchanged risk. We investigated the association between bisphosphonate treatment and the risk of stroke using a large routine clinical dataset.MethodsWe used a matched nested case-control study design analysing routinely collected electronic data from patients registered at primary care practices in England participating in the Royal College of General Practitioners Research and Surveillance Centre. Cases were patients aged 18 years or over, either living or dead, recorded as having had a stroke in the period 1 January 2005 to 31 March 2016. Each case was matched to one control according to age, sex, general practice attended and calendar time. Data were analysed using Stata, version 14.2. and RStudio, version 1.1.463. Conditional logistic regression was used to determine odds ratios for stroke according to bisphosphonate treatment and duration in cases compared with controls. We adjusted for disease risk groups, cardiovascular risk factors, treatments, smoking status, alcohol consumption, ethnicity, bisphosphonate types, fracture and socioeconomic status using IMD (Index of Multiple Deprivation).ResultsWe included 31,414 cases of stroke with an equal number of matched controls. Overall, 83.2% of cases and controls were aged 65 years or older, and there were similar proportions of females (51.5%) and males (48.5%). Bisphosphonate treatment was not associated with stroke after adjusting for the wide range of confounders considered (OR 0.86, 95% CI 0.62–1.19).ConclusionsWe found no association between bisphosphonate treatment and risk of stroke, after adjusting for other confounders.

It is shown that variance estimates for regression coefficients in exposure-stratified case-cohort studies (Borgan et al 9 Lifetime Data Anal., 6,2000,39-58) can easily be obtained from influence terms routinely calculated in the standard software for Cox regression. By allowing for post-stratification on outcome we also place the estimators proposed by Chen (J. R. Statist. Soc. Ser. B, 63, 2001,791-809) for a general class of cohort sampling designs within the Borgan et al.'s framework, facilitating simple variance estimation for these designs. Finally, the Chen approach is extended to accommodate stratified designs with surrogate variables available for all cohort members, such as stratified case-cohort and counter-matching designs.

Purpose: The nested case–control study design, in which a fixed number of controls are matched to each case, is often used to analyze exposure–response associations within a cohort. It has become common practice to sample four or five controls per case; however, previous research has shown that in certain instances, significant gains in relative efficiency can be realized when more controls are matched to each case. This study expanded upon this and investigated the effect of (i) the number of cases, (ii) the strength of the exposure–response, and (iii) the skewness of the exposure distribution on the bias and relative efficiency of the conditional likelihood estimator from a nested case–control study. Methods: Cohorts were simulated and analyzed using conditional logistic regression. Results: The relative efficiency decreased and bias away from the null increased, as the true exposure–response parameter increased and the skewness of the exposure distribution of the risk-sets increased. This became more pronounced when the number of cases in the cohort was small. Conclusions: Gains in relative efficiency and a reduction in bias can be realized by sampling more than four or five controls per case generally used, especially when there are few cases, a strong exposure–response relation, and a skewed exposure variable.

Patients with chronic obstructive pulmonary disease (COPD) are frequently treated with inhaled corticosteroids (ICS). However, the impact of ICS use on fracture risk remains unclear in these patients. This nested case-control study examines the association between ICS use and nonvertebral fractures in Veterans Affairs patients with COPD. From a cohort of 40,157 patients with a COPD diagnosis between October 1, 1998 and September 30, 1999, and that used services in the preceding 12-month period but did not have a COPD diagnosis, 1,708 cases with nonvertebral fractures were identified and matched to 6,817 control patients. Patients were 94% male, and average age was 62.7 years. ICS exposure was identified through prescription records and converted to beclamethasone equivalents. In conditional logistic regression models, exposure to ICS at any time during follow-up was not associated with an increased fracture risk (adjusted odds ratio = 0.97; 95% confidence interval, 0.84-1.11). However, current high-dose ICS users (> or = 700 microg per day) had an increased risk of fractures compared with patients with no exposure (adjusted odds ratio = 1.68; 95% confidence interval, 1.10-2.57). In patients with COPD, current use of high-dose ICS was associated with an increased risk of nonvertebral fractures.