Cigarette smoking and risk of severe infectious respiratory diseases in UK adults: 12-year follow-up of UK biobank

Morbidity amongst South African Hajj pilgrims in 2023-a retrospective cohort study

South Africans are not accustomed to the dry arid climate and sweltering heat in Saudi Arabia. We conducted a retrospective cohort study to identify the common health conditions pre-Hajj, during the 5 days of Hajj and on return to South Africa from Hajj amongst the 2023 pilgrims. A QR code and a mobile link to a self-administered questionnaire was sent to all 3500 South African pilgrims. Five hundred and seventy-seven pilgrims returned the completed surveys. Mean age of the participants was 48 years (SD 12) with a higher female representation (3:2). Forty eight percent (279) had pre-existing chronic conditions. Forty five percent (259) reported being ill during their stay in the Kingdom, 20% (115) reported having an illness during the main 5 days, whilst 51% (293) reported having an illness within 7 days of returning to South Africa. Only six pilgrims were admitted to hospital after their return home. Respiratory tract linked symptoms were the most frequently reported (95% pre Hajj and 99% post Hajj). Participants who reported having a chronic condition (AOR 1.52 95% CI 1.09-2.11) and engaging in independent exercising prior to Hajj (AOR 1.52-1.07-2.10) were at an increased likelihood of developing an illness within 7 days of returning home. Post travel surveillance swabs to identify potential pathogens that the returning pilgrims are incubating should be explored to guide further interventions.

Smoking, Corneal Biomechanics, and Glaucoma: Results From Two Large Population-Based Cohorts

Purpose

Smoking may influence measured IOP through an effect on corneal biomechanics, but it is unclear whether this factor translates into an increased risk for glaucoma. This study aimed to examine the association of cigarette smoking with corneal biomechanical properties and glaucoma-related traits, and to probe potential causal effects using Mendelian randomization (MR).

Methods

Cross-sectional analyses within the UK Biobank (UKB) and Canadian Longitudinal Study on Aging (CLSA) cohorts. Multivariable linear and logistic regression models were used to assess associations of smoking (status, intensity, and duration) with corneal hysteresis (CH), corneal resistance factor, IOP, inner retinal thicknesses, and glaucoma. Two-sample MR analyses were performed.

Results

Overall, 68,738 UKB (mean age, 56.7 years; 54.7% women) and 22 845 CLSA (mean age, 62.7 years; 49.1% women) participants were included. Compared with nonsmokers, smokers had a higher CH (UKB, +0.48 mm Hg; CLSA, +0.57 mm Hg; P < 0.001) and corneal resistance factor (UKB, +0.47 mm Hg; CLSA, +0.60 mm Hg; P < 0.001) with evidence of a dose-response effect in both studies. Differential associations with Goldmann-correlated IOP (UKB, +0.25 mm Hg; CLSA, +0.36 mm Hg; P < 0.001) and corneal-compensated IOP (UKB, -0.28 mm Hg; CLSA, -0.32 mm Hg; P ≤ 0.001) were observed. Smoking was not associated with inner retinal thicknesses or glaucoma status in either study. MR provided evidence for a causal effect of smoking on corneal biomechanics, especially higher CH.

Conclusions

Cigarette smoking seems to increase corneal biomechanical resistance to deformation, but there was little evidence to support a relationship with glaucoma. This outcome may result in an artefactual association with measured IOP and could account for discordant results with glaucoma in previous epidemiological studies.