Association of metformin use and cancer incidence: a systematic review and meta-analysis

BACKGROUND

Metformin is among the most widely used antidiabetics medications because of its minimal toxicity, favorable safety profile, availability, and low cost. In addition to its role in diabetes management, metformin may reduce cancer risk.

METHODS

We conducted a comprehensive systematic review and meta-analysis to investigate the association between metformin use and cancer risk, with evaluation by specific cancer type when possible. Applicable studies were identified in PubMed/MEDLINE, Embase, Cochrane Library, Web of Science, and Scopus from inception through March 7, 2023, with metformin use categorized as "ever" or "yes" and a cancer diagnosis as the outcome. Article quality was evaluated using National Heart, Lung, and Blood Institute guidelines, and publication bias was evaluated using the Egger test, Begg test, and funnel plots. Pooled relative risk (RR) estimates were calculated using random-effects models, and sensitivity analysis was completed through leave-one-out cross-validation.

RESULTS

We included 166 studies with cancer incidence information in the meta-analysis. Reduced risk for overall cancer was observed in case-control studies (RR = 0.55, 95% confidence interval [CI] = 0.30 to 0.80) and prospective cohort studies (RR = 0.65, 95% CI = 0.37 to 0.93). Metformin use was associated with reduced gastrointestinal (RR = 0.79, 95% CI = 0.73 to 0.85), urologic (RR = 0.88, 95% CI = 0.78 to 0.99), and hematologic (RR = 0.87, 95% CI = 0.75 to 0.99) cancer risk. Statistically significant publication bias was observed within the studies (Egger P < .001).

CONCLUSIONS

Metformin may be associated with a decreased risk of many cancer types, but high heterogeneity and risk of publication bias limit confidence in these results. Additional studies in populations without diabetes are needed to better understand the utility of metformin in cancer prevention.

Adherence to non-pharmaceutical interventions for COVID-19: a national survey

Background

The global Covid-19 pandemic response depends heavily on non-pharmaceutical interventions to protect population health. This aim of this study was to provide insights into levels and determinants of adherence to travel restrictions and wearing of face coverings during the early phase of the pandemic response in Ireland.

Methods

A series of four cross-sectional surveys were administered through random digit dialling of mobile and landline numbers during May-June 2020. Questions were asked about compliance with local travel restrictions and where relevant, the reasons for travel. A question on mask use was added to the final wave of data collection.

Results

Overall, across the four waves, 73.4% reported adhering to the travel restrictions and these levels were maintained over time (wave 1: 72.1%, wave 2: 73.7%, wave 3: 67.3%, wave 4: 79.7%) and were broadly similar across different socioeconomic groups. Higher proportions reported travelling for non-exempt reasons over time particularly in the final wave of data collection including exercise (from 3% in wave 1, 5% in wave 2 up to 8% in waves 3 and 4) and recreational or social activities (2% in waves 1 and 2, 4% in wave 3, up to 15% by wave 4). Overall, over two-thirds of respondents reported use of masks in the final wave, (72% of women, 65% of men) with shops or supermarkets the most common place of use. Among primary respondents, older age (Age 70+ vs. 18k-44, OR 3.2 [2.4-4.3]), attending higher education (attending vs. completed third level OR 2.2 [ 1.6-3.0]) and female gender (OR 1.2 [1.1-1.4]) were independently associated with compliance with travel restrictions.

Conclusions

The findings demonstrate high levels of adherence to travel restrictions during the early stages of the emerging COVID-19 pandemic, albeit with a modest trend towards reduced compliance over time. There was a high uptake of mask use in advance of relevant national guidance.

Mortality in residential care services for people with disabilities in Ireland

Background

All-cause mortality is higher in people with disability than in people without disability. There is a need for descriptive epidemiological studies of deaths in people with disability to inform the development of public health interventions. All deaths in residential disability services in Ireland are notified to the Chief Inspector in the Health Information and Quality Authority (HIQA). These include notification of unexpected and expected deaths. The herein aim was to describe total, unexpected and expected deaths, and identify leading causes of death in residential disability services in Ireland.

Methods

Data on deaths in residential disability services in 2019 and 2020 were extracted from the Database of Statutory Notifications from Social Care in Ireland. The number of total deaths was calculated along with the percent and number of unexpected and expected deaths. The primary cause of death notified by services was coded using ICD-11 chapter headings.

Results

During 2019 and 2020, on average 9,115 people resided in residential disability services. Of these, 395 died, of which 45% (n = 178) were notified as unexpected. The leading causes of unexpected deaths were respiratory system diseases (35%, n = 62) and circulatory system diseases (18%, n = 32). The leading causes of expected death were respiratory system diseases (41%, n = 89) and cancers (31%, n = 67).

Conclusions

Almost half of deaths in residential disability services were notified as unexpected. Respiratory disease was the leading cause of both expected and unexpected death in people with disability residing in residential services in Ireland; three-fold the general Irish population (10.7%). Public health interventions aimed at reducing respiratory disease may reduce deaths in this group.

Key messages

In 2019 and 2020, nearly half of deaths of people with a disability residing in residential services were notified as unexpected. Death from respiratory diseases was substantially higher in people with disability living in residential services in Ireland than in the general population and warrants public health intervention.