Sex differences in the risk of retinopathy of prematurity: a systematic review, frequentist and Bayesian meta-analysis, and meta-regression

BACKGROUND

Retinopathy of prematurity (ROP) is generally considered to be more frequent in males than in females. However, it is not known whether sex differences in ROP affect all degrees of the condition, are global and have changed as neonatology has developed. We aimed to conduct a systematic review and meta-analysis of studies addressing sex differences in the risk of developing ROP.

METHODS

PubMed/MEDLINE and Embase databases were searched. The frequentist, random-effects risk ratio (RR) and 95% confidence interval (CI) were calculated. Bayesian model averaged (BMA) meta-analysis was used to calculate the Bayes factors (BFs). The BF10 is the ratio of the probability of the data under the alternative hypothesis (H1) over the probability of the data under the null hypothesis (H0).

RESULTS

We included 205 studies (867,252 infants). Frequentist meta-analysis showed a positive association between male sex and severe ROP (113 studies, RR = 1.14, 95% CI = 1.07-1.22) but no association with any ROP (144 studies, RR = 1.00, 95% CI = 0.96-1.03). BMA showed extreme evidence in favor of H1 for severe ROP (BF10 = 71,174) and strong evidence in favor of H0 for any ROP (BF10 = 0.05). The association between male sex and severe ROP remained stable over time and was present only in cohorts from countries with a high or high-middle sociodemographic index.

CONCLUSIONS

Our study confirms the presence of a male disadvantage in severe ROP but not in less severe forms of the disease. There are variations in the sex differences in ROP, depending on geographical location and sociodemographic level of the countries.

Platelet Counts and Risk of Severe Retinopathy of Prematurity: A Bayesian Model-Averaged Meta-Analysis

BACKGROUND

We aimed to conduct a systematic review and Bayesian model-averaged meta-analysis (BMA) on the association between platelet counts and severe retinopathy of prematurity (ROP).

METHODS

We searched for studies reporting on platelet counts (continuous variable) or thrombocytopenia (categorical variable) and severe ROP or aggressive posterior ROP (APROP). The timing of platelet counts was divided into Phase 1 (<2 weeks) and Phase 2 (around ROP treatment). BMA was used to calculate Bayes factors (BFs). The BF10 is the ratio of the probability of the data under the alternative hypothesis (H1) over the probability of the data under the null hypothesis (H0).

RESULTS

We included 21 studies. BMA showed an association between low platelet counts and severe ROP. The evidence was strong (BF10 = 13.5, 7 studies) for phase 1 and very strong (BF10 = 51.0, 9 studies) for phase 2. Thrombocytopenia (<100 × 109/L) in phase 2 was associated with severe ROP (BF10 = 28.2, 4 studies). Following adjustment for publication bias, only the association of severe ROP with thrombocytopenia remained with moderate evidence in favor of H1 (BF10 = 4.30).

CONCLUSIONS

Thrombocytopenia is associated with severe ROP. However, the evidence for this association was tempered when results were adjusted for publication bias.

The Representation of Females in Studies on Antihypertensive Medication over the Years: A Scoping Review

BACKGROUND

The leading global risk factor for cardiovascular-disease-related morbidity and mortality is hypertension. In the past decade, attention has been paid to increase females' representation. The aim of this study is to investigate whether the representation of females and presentation of sex-stratified data in studies investigating the effect of antihypertensive drugs has increased over the past decades.

METHODS

After systematically searching PubMed and Embase for studies evaluating the effect of the five major antihypertensive medication groups until May 2020, a scoping review was performed. The primary outcome was the proportion of included females. The secondary outcome was whether sex stratification was performed.

RESULTS

The search resulted in 73,867 articles. After the selection progress, 2046 studies were included for further analysis. These studies included 1,348,172 adults with a mean percentage of females participating of 38.1%. Female participation in antihypertensive studies showed an increase each year by 0.2% (95% CI 0.36-0.52), p < 0.01). Only 75 (3.7%) studies performed sex stratification, and this was the highest between 2011 and 2020 (7.2%).

CONCLUSION

Female participation showed a slight increase in the past decade but is still underrepresented compared to males. As data are infrequently sex-stratified, more attention is needed to possible sex-related differences in treatment effects to different antihypertensive compounds.

The underrepresentation of females in antihypertensive medication over the years: a scoping review

Background

Hypertension is one of the leading global risk factors for cardiovascular disease-related morbidity and mortality. Females have historically been underrepresented in clinical trials resulting in presumed sex-related disparities in antihypertensive treatment effects. The past decade, widespread attention has been paid to this shortcoming aiming at increasing females' representation in clinical trials.

Purpose

To investigate whether in studies investigating the effect of antihypertensive drugs 1) the representation of females and 2) presentation of sex-stratified data has increased over the past decades.

Methods

We performed a scoping review after systematically searching PubMed and Embase for studies evaluating the effects of the five major groups of antihypertensive medication from inception (1945) until May 2020. The review was registered in Prospero database. Studies were only included if they 1) investigated one class of the five main groups of antihypertensive medications (beta-blockers, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, calcium channel blockers, and diuretics, 2) human studies, 3) investigated adults ≥18 years of age, 4) were written in English or Dutch. We excluded articles if 1) only abstract was available and full report was not found, 2) unsuitable study design, 3) no reference group included, 4) outcome not related to cardiovascular health, 5) no registration of specific dose and duration information.

The primary outcome was the proportion of included females over time, stratified per decade. The secondary outcome was whether sex-stratification was reported. Linear regression analysis with beta coefficient (β) and 95% CI was performed to explore the associations between the percentage of females included in the studies over time.

Results

The search strategy resulted in 73,867 potential articles. After study selection based on title/abstract and full text, 2,079 original studies were eligible for our study. These included 1,395,264 adults of which the mean percentage of females participating in all included studies was 27.9% (Figure 1, Table 1). The percentage of females participating in antihypertensive studies showed a slight increase each year by 0.4% (95% CI 0.36–0.53, P&lt;0.01). The yearly increase was the highest between 2001 and 2010 being 0.52% (95% CI 0.076–0.954) and in the most recent decade (between 2011 and 2020) 38.7% of included participants were female. Sex-stratification was performed in 76 (3.7%) studies and was the highest between 2011 and 2020 (7.3%).

Conclusion

Despite yearly increase in female participation in antihypertensive studies, females still only account for only one third of the study population. Moreover, less than 10% of studies report sex stratified data. Considering the global burden of hypertension, more differentiated sex-specific attention remains critically needed.

Funding Acknowledgement

Type of funding sources: None.