Concepts of comorbidities, multiple morbidities, complications, and their clinical epidemiologic analogs

Venous thrombosis and risk of cancer in patients with arterial cardiovascular disease

INTRODUCTION

Patients with acute myocardial infarction or stroke are at high risk of venous thromboembolism, which is traditionally considered a complication rather than a marker of occult cancer. We examined the association between venous thromboembolism and cancer in patients with acute myocardial infarction or stroke.

METHODS

We used medical databases to conduct a population-based cohort study including all patients with a first-time venous thromboembolism from 1978 through 2011 who also had a diagnosis of acute myocardial infarction (n=2,878) or stroke (n=1,971) recorded on the same day or within the previous 90days. We followed patients until a first-time cancer diagnosis, emigration, death, or December 31, 2011, whichever came first. We computed 1-year absolute risks and standardised incidence ratios for cancer based on national incidence rates.

RESULTS

The 1-year absolute cancer risk was 2.7% in the acute myocardial infarction cohort and 3.7% in the stroke cohort. The corresponding standardised incidence ratios were 3.22 (95% confidence interval [CI]: 2.54-4.03) and 3.76 (95% CI: 2.95-4.74), respectively. For cancers diagnosed in the first year, the estimated number of venous thromboembolism patients needed to examine to detect one excess cancer was 25 in the acute myocardial infarction cohort and 19 in the stroke cohort.

CONCLUSION

Among acute myocardial infarction and stroke patients, venous thromboembolism can be a marker of occult cancer. We suggest that current guidelines for cancer screening in patients with unprovoked venous thromboembolism could be applied to this group of patients.

Conization as a marker of persistent cervical human papillomavirus (HPV) infection and risk of gastrointestinal cancer: a Danish 34-year nationwide cohort study

PURPOSE

Persistent cervical infection with human papillomavirus (HPV) may be a marker of poor immune function and thus associated with an increased cancer risk. HPV infection is implicated in all cases of cervical cancer, but except for anal and esophageal cancers, the association between persistent HPV infection and gastrointestinal cancer has not been investigated.

METHODS

We performed a nationwide population-based cohort study of 83,008 women undergoing cervical conization between 1978 and 2011, using cervical conization as a marker of chronic HPV infection. We computed standardized incidence ratios (SIRs) as a measure of the relative risk of each cancer comparing women undergoing conization with that expected in the general population. We also calculated absolute risks.

RESULTS

During follow-up, 988 GI cancers occurred versus 880 expected among 83,008 women followed for a median of 14.9 years, corresponding to a SIR of 1.1 (95 % CI 1.1-1.2). Risks were increased for anal (SIR 2.9; 95 % CI 2.3-3.5) and esophageal (SIR 1.5; 95 % CI 1.1-2.0) cancers, with suggested increased risks of cancers of the gallbladder and biliary tract (SIR 1.3; 95 % CI 0.90-1.8), pancreas (SIR 1.2; 95 % CI 0.97-1.4), and liver (SIR 1.1; 95 % CI 0.79-1.6). The SIRs decreased with increasing follow-up time. The risks of gastric, small intestinal, colon, or rectal cancers were not elevated. Overall, the absolute cancer risk was 0.18 % (95 % CI 0.15-0.21) after 5 years.

CONCLUSIONS

The relative risks of several gastrointestinal cancers were raised among women who underwent cervical conization for persistent HPV infection, but the absolute risks were low.

Comorbidity in cirrhosis

Cirrhosis patients’ comorbidities are their other diseases than cirrhosis. Comorbidities are neither causes nor consequences of cirrhosis, but they can increase mortality and are therefore clinically important. They are also an important source of confounding in epidemiologic studies. Comorbidity scoring systems have been developed as tools to measure the cirrhosis patient’s total burden of comorbidity, and they are useful in the clinic and for epidemiologic studies. The recently developed CirCom score is the only comorbidity scoring system developed specifically for cirrhosis patients, and it may be preferred over the older, generic, and more complex Charlson comorbidity index. Studies of individual comorbid diseases can provide insight into the interactions between cirrhosis and other diseases and thus into the pathophysiology of cirrhosis. This article reviews the literature on comorbidity in cirrhosis.

Comorbidity of dementia: a cross-sectional study of primary care older patients

BACKGROUND

The epidemiologic study of comorbidities of an index health problem represents a methodological challenge. This study cross-sectionally describes and analyzes the comorbidities associated with dementia in older patients and reviews the existing similarities and differences between identified comorbid diseases using the statistical methods most frequently applied in current research.

METHODS

Cross-sectional study of 72,815 patients over 64 seen in 19 Spanish primary care centers during 2008. Chronic diseases were extracted from electronic health records and grouped into Expanded Diagnostic Clusters®. Three different statistical methods were applied (i.e., analysis of prevalence data, multiple regression and factor analysis), stratifying by sex.

RESULTS

The two most frequent comorbidities both for men and women with dementia were hypertension and diabetes. Yet, logistic regression and factor analysis demonstrated that the comorbidities significantly associated with dementia were Parkinson's disease, congestive heart failure, cerebrovascular disease, anemia, cardiac arrhythmia, chronic skin ulcers, osteoporosis, thyroid disease, retinal disorders, prostatic hypertrophy, insomnia and anxiety and neurosis.

CONCLUSIONS

The analysis of the comorbidities associated with an index disease (e.g., dementia) must not be exclusively based on prevalence rates, but rather on methodologies that allow the discovery of non-random associations between diseases. A deep and reliable knowledge about how different diseases are grouped and associated around an index disease such as dementia may orient future longitudinal studies aimed at unraveling causal associations.