Handling sparse spatial data in ecological applications

Estimating the size of an insect pest population in an agricultural field is an integral part of insect pest monitoring. An abundance estimate can be used to decide if action is needed to bring the population size under control, and accuracy is important in ensuring that the correct decision is made. Conventionally, statistical techniques are used to formulate an estimate from population density data obtained via sampling. This thesis thoroughly investigates an alternative approach of applying numerical integration techniques. We show that when the pest population is spread over the entire field, numerical integration methods provide more accurate results than the statistical counterpart. Meanwhile, when the spatial distribution is more aggregated, the error behaves as a random variable and the conventional error estimates do not hold. We thus present a new probabilistic approach to assessing integration accuracy for such functions, and formulate a mathematically rigorous estimate of the minimum number of sample units required for accurate abundance evaluation in terms of the species diffusion rate. We show that the integration error dominates the error introduced by noise in the density data and thus demonstrate the importance of formulating numerical integration techniques which provide accurate results for sparse spatial data

Single-inhaler triple therapy in patients with chronic obstructive pulmonary disease:a systematic review

Abstract Background Guidelines recommend that treatment with a long-acting β2 agonist (LABA), a long-acting muscarinic antagonist (LAMA), and inhaled corticosteroids (ICS), i.e. triple therapy, is reserved for a select group of symptomatic patients with chronic obstructive pulmonary disease (COPD) who continue to exacerbate despite treatment with dual therapy (LABA/LAMA). A number of single-inhaler triple therapies are now available and important clinical questions remain over their role in the patient pathway. We compared the efficacy and safety of single-inhaler triple therapy to assess the magnitude of benefit and to identify patients with the best risk-benefit profile for treatment. We also evaluated and compared study designs and population characteristics to assess the strength of the evidence base. Methods We conducted a systematic search, from inception to December 2018, of randomised controlled trials (RCTs) of single-inhaler triple therapy in patients with COPD. The primary outcome was the annual rate of moderate and severe exacerbations. Results We identified 523 records, of which 15 reports/abstracts from six RCTs were included. Triple therapy resulted in the reduction of the annual rate of moderate or severe exacerbations in the range of 15–52% compared with LAMA/LABA, 15–35% compared to LABA/ICS and 20% compared to LAMA. The patient-based number needed to treat for the moderate or severe exacerbation outcome ranged between approximately 25–50 (preventing one patient from having an event) and the event-based number needed to treat of around 3–11 (preventing one event). The absolute benefit appeared to be greater in patients with higher eosinophil counts or historical frequency of exacerbations and ex-smokers. In the largest study, there was a significantly higher incidence of pneumonia in the triple therapy arm. There were important differences in study designs and populations impacting the interpretation of the results and indicating there would be significant heterogeneity in cross-trial comparisons. Conclusion The decision to prescribe triple therapy should consider patient phenotype, magnitude of benefit and increased risk of adverse events. Future research on specific patient phenotype thresholds that can support treatment and funding decisions is now required from well-designed, robust, clinical trials. Trial registration PROSPERO #CRD42018102125 .https://deepblue.lib.umich.edu/bitstream/2027.42/152151/1/12931_2019_Article_1213.pd

Systemic lupus erythematosus; stroke and myocardial infarction risk: a systematic review and meta-analysis.

OBJECTIVE: To evaluate the risk of stroke and myocardial infarction (MI) in adult patients with systemic lupus erythematosus (SLE) through a systematic review and meta-analysis. METHODS: We searched MEDLINE and EMBASE from inception to May 2020 to identify observational studies (cohort and cross-sectional) that evaluated risk of stroke and MI in adult patients with SLE compared with the general population or healthy controls. Studies were included if they reported effect-size estimates that could be used for calculating pooled-effect estimates. Random-effects models were used to calculate pooled risk ratios (RRs) and 95% CIs for stroke and MI. Heterogeneity quantified by the I2 test and sensitivity analyses assessed bias. RESULTS: In total, 26 studies were included in this meta-analysis: 14, 5 and 7 studies on stroke, MI and both stroke and MI, respectively. The pooled RR for ischaemic stroke was 2.18 (95% CI 1.78 to 2.67; I2 75%), intracerebral haemorrhage 1.84 (95% CI 1.16 to 2.90; I2 67%), subarachnoid haemorrhage 1.95 (95% CI 0.69 to 5.52; I2 94%), composite stroke 2.13 (95% CI 1.73 to 2.61; I2 88%) and MI 2.99 (95% CI 2.34 to 3.82; I2 85%). There was no evidence for publication bias, and sensitivity analyses confirmed the robustness of the results. CONCLUSIONS: Overall, patients with SLE were identified to have a twofold to threefold higher risk of stroke and MI. Future research on the interaction between known SLE-specific modifiable risk factors and risk of stroke and MI to support development of prevention and treatment strategies are needed. PROSPERO REGISTRATION NUMBER: CRD42018098690

Risk of malignancy in patients with systemic lupus erythematosus: Systematic review and meta-analysis.

BACKGROUND: Malignancy is a potential comorbidity in patients with systemic lupus erythematosus (SLE). However, risk by malignancy type remains to be fully elucidated. We evaluated the risk of malignancy type in SLE patients in a systematic review and meta-analysis. METHODS: MEDLINE and EMBASE were searched from inception to July 2018 to identify observational studies that evaluated malignancy risk in adult SLE patients compared with the general population. Random-effects models were used to calculate pooled risk ratios (RRs) and 95% confidence intervals (CIs). Heterogeneity was quantified using the I2 test. FINDINGS: Forty-one studies reporting on 40 malignancies (one overall, 39 site-specific) were included in the meta-analysis. The pooled RR for all malignancies from 3694 events across 80 833 patients was 1.18 (95% CI: 1.00-1.38). The risk of 24 site-specific malignancies (62%) was increased in SLE patients. For malignancies with ≥6 studies, non-Hodgkin lymphoma and Hodgkin lymphoma risk was increased >3-fold; myeloma and liver >2-fold; cervical, lung, bladder, and thyroid ≥1.5-fold; stomach and brain >1.3-fold. The risk of four malignancies (breast, uterine, melanoma, prostate) was decreased, whereas risk of 11 other malignancies did not differ between SLE patients and the general population. Heterogeneity ranged between 0% and 96%, and 63% were non-significant. INTERPRETATION: The risk of overall and some site-specific malignancies is increased in SLE compared with the general population. However, the risk for some site-specific malignancies is decreased or did not differ. Further examination of risk profiles and SLE patient phenotypes may support guidelines aimed at reducing malignancy risk. FUNDING: AstraZeneca. SYSTEMATIC REVIEW REGISTRATION: PROSPERO number: CRD42018110433

The risk of infections in adult patients with systemic lupus erythematosus: systematic review and meta-analysis.

OBJECTIVES: We conducted a systematic review and meta-analysis to determine the magnitude of infection risk in patients with SLE and evaluate the effect of general and SLE-related factors on infection risk. METHODS: We searched MEDLINE and Embase from inception to July 2018, screening for observational studies that evaluated infection risk in patients with SLE compared with the general population/healthy controls. Outcomes of interest included overall severe infection, herpes zoster infection/reactivation, opportunistic infections, pneumonia and tuberculosis. Random-effects models were used to calculate pooled risk ratios (RRs) for each type of infection. Sensitivity analysis assessed the impact of removing studies with high risk of bias. RESULTS: Eleven retrospective or prospective cohort studies were included in the meta-analysis: overall severe infection (n = 4), pneumonia (n = 6), tuberculosis (n = 3) and herpes zoster (n = 2). Pooled RRs for overall severe infection significantly increased for patients with SLE compared with the general population/healthy controls [RR 2.96 (95% CI 1.28, 6.83)]. Pooled RRs for pneumonia, herpes zoster and tuberculosis showed significantly increased risk compared with the general population/healthy controls [RR 2.58 (1.80, 3.70), 2.50 (2.36, 2.65) and 6.11 (3.61, 10.33), respectively]. Heterogeneity and evidence of publication bias were present for all analyses, except herpes zoster. Sensitivity analyses confirmed robustness of the results. CONCLUSION: Patients with SLE have significantly higher risk of infection compared with the general population/healthy controls. Efforts to strengthen strategies aimed at preventing infections in SLE are needed. PROTOCOL REGISTRATION: PROSPERO number: CRD42018109425

Association of COPD exacerbations and acute cardiovascular events: a systematic review and meta-analysis

Background: The majority of patients with chronic obstructive pulmonary disease (COPD) suffer from comorbid cardiovascular (CV) disease. Accumulating evidence suggests a temporal association between COPD exacerbations and acute CV events, possibly due to lung hyperinflation, increased hypoxemia and systemic inflammation. The aims of the study were to estimate the risk of (1) acute CV events [acute myocardial infarction (AMI), CV-related death] or stroke in the months following a COPD exacerbation and (2) COPD exacerbation in the months following an acute CV event. Methods: A systematic literature review of observational studies published since 2000 was conducted by searching literature databases (Medline and Embase). Studies were eligible if conducted in adults with COPD, exposed to either COPD exacerbation or acute CV events, with outcomes of acute CV events or COPD exacerbation reported. Studies were appraised for relevance, bias and quality. Meta-analyses, using random-effect models, were performed for each outcome of interest, thus providing a pooled relative risk (RR) and its 95% confidence interval. Results: Eight studies were identified, of which seven were used for the meta-analyses examining the risk of CV events 1–3 months after an exacerbation compared with none. For stroke (six studies), RR was 1.68 (95% CI = 1.19–2.38). For AMI (six studies), RR was 2.43 (95% CI = 1.40–4.20). No studies exploring risk of exacerbation following an acute CV event were identified. Conclusion: This meta-analysis identified a markedly increased risk of stroke or AMI within a relatively short period of time following a COPD exacerbation. Although the underlying mechanisms are not fully elucidated, patients with COPD should be monitored for risk of CV outcomes after exacerbations. In addition, preventing exacerbations may decrease the risk of subsequent acute CV events. Registration: The study protocol was published via PROSPERO: International Prospective Register of Systematic Reviews (#CRD42020211055)