How competing risks affect the epidemiological relationship between vitamin D and prostate cancer incidence? A population-based study

Multiplicative, additive, and interactive associations of 25-hydroxyvitamin D with lung and prostate cancer

Results regarding the epidemiological association of vitamin D with lung (LCA) and prostate cancer (PCA) are controversial. This study tested whether serum 25-hydroxyvitamin D [25(OH)D] concentrations have interactive epidemiological associations with smoking, the number-one risk factor for LCA, and age, the number-one risk factor for PCA. Also, this study investigated whether the associations of 25(OH)D, smoking, age, alcohol consumption, body mass index, diet (the healthy Nordic diet score), and physical activity with incident LCA and PCA are multiplicative or additive. The study of association types makes it easier to select appropriate statistical methods. The Kuopio Ischaemic Heart Disease Risk Factor Study provided the data of 2578 men with 112 LCA and 300 PCA cases over 35 years by the end of 2019. Serum 25(OH)D did not associate with LCA and PCA or interact with smoking and age. The association of smoking with LCA was additive; 13 extra cases per 1000 men every 10 years. Age and alcohol consumption multiplicatively increased the hazard of LCA (hazard ratio, 95% confidence interval for age >50: 3.56, 1.82-6.17; drink per week: 1.01, 1.00-1.03), whereas adherence to healthy Nordic diet decreased it (per score point: 0.95, 0.89-1.00). The association of age >50 with PCA was additive; 2.5 extra cases per 1000 men every 10 years. To conclude, there was no epidemiological relationship of pre-diagnostic 25(OH)D concentrations with the incidence of LCA and PCA. The respective associations of smoking and age >50 with LCA and PCA were additive rather than multiplicative.

What is the most appropriate follow-up time for detecting the epidemiological relationship between coronary artery disease and its main risk factors: novel findings from a 35-year follow-up study

BACKGROUND

The aim was to investigate the most appropriate follow-up time to detect the associations of coronary artery disease (CAD) with its traditional risk factors in a long-term prospective cohort study.

METHODS

The Kuopio Ischaemic Heart Disease Risk Factors Study provided the study material of 1958 middle-aged men free from CAD at baseline and followed up for 35 years. We performed Cox models adjusted for age, family history, diabetes, obesity, hypercholesterolemia, hypertension, smoking, and physical activity, investigated covariate interactions, and tested Schoenfeld residuals to detect time-dependent covariates. Moreover, we applied a sliding window procedure with a subarray of 5 years to better differentiate between risk factors manifested within years and those manifested within decades. The investigated manifestations were CAD and fatal acute myocardial infarction (AMI).

RESULTS

Seven hundred seventeen (36.6%) men had CAD, and 109 (5.6%) men died from AMI. After 10 years of follow-up, diabetes became the strongest predictor of CAD with a fully adjusted hazard ratio (HR) of 2.5-2.8. During the first 5 years, smoking was the strongest predictor (HR 3.0-3.8). When the follow-up time was 8-19 years, hypercholesterolemia predicted CAD with a HR of >2. The associations of CAD with age and diabetes depended on time. Age hypertension was the only statistically significant covariate interaction. The sliding window procedure highlighted the significance of diabetes over the first 20 years and hypertension after that. Regarding AMI, smoking was associated with the highest fully adjusted HR (2.9-10.1) during the first 13 years. The associations of extreme and low physical activity with AMI peaked when the follow-up time was 3-8 years. Diabetes showed its highest HR (2.7-3.7) when the follow-up time was 10-20 years. During the last 16 years, hypertension was the strongest predictor of AMI (HR 3.1-6.4).

CONCLUSION

The most appropriate follow-up time for most CAD risk factors was 10-20 years. Concerning smoking and hypertension shorter and longer follow-up times could be considered, respectively, particularly when studying fatal AMI. In general, prospective cohort studies of CAD would provide more comprehensive results by reporting point estimates in relation to more than one timepoint and concerning sliding windows.

Vitamin D Deficiency at Diagnosis Increases All-Cause and Prostate Cancer-specific Mortality in Jamaican Men

Background

25 hydroxyvitamin D [25(OH)D] and serum calcium have been associated with incident prostate cancer (PCa). However, there is limited data on whether these metabolites predict survival in men of African descent, a population disproportionately affected by PCa. We studied the relationship of 25(OH)D at PCa diagnosis with all-cause and cancer-specific mortality among Jamaican men and examined whether serum calcium modified any associations.

Methods

Serum 25(OH)D from 152 Jamaican men with incident PCa within the Prostate Cancer Risk Evaluation (PROSCARE) study were re-evaluated approximately 11 years after enrollment. 25(OH)D analyses were stratified using the using Holick criteria. PCa-specific and all-cause mortality were examined in Kaplan–Meier survival curves and Cox regression models adjusted for age, body mass index (BMI), smoking and Gleason score. Restricted cubic splines evaluated nonlinear associations. Serum calcium was assessed as an effect modifier of the association between 25(OH)D and mortality.

Results

Of cases with available 25(OH)D, 64 men with PCa survived, 38 deaths were PCa specific and 36 died of other causes. At baseline, 9.9% of cases were vitamin D deficient and 61.2% were vitamin D sufficient. Compared to 25(OH)D sufficient men, those with 25(OH)D <20.0 ng/mL concentrations were associated with higher PCa-specific mortality (adjusted HR, 4.95; 95% CI, 1.68, 14.63, P = .004) and all-cause mortality (adjusted HR, 2.40; 95%CI, 1.33, 4. 32, P = .003). Serum calcium was not associated with survival and did not modify any associations with 25(OH)D.

Conclusions

25(OH)D deficiency at PCa diagnosis predicted decreased survival for overall and PCa-specific cancer in Caribbean men of African ancestry.