Multi-Institutional Report of Re-Irradiation for Recurrent High-Grade Glioma

PURPOSE/OBJECTIVE(S)

Significant heterogeneity exists with regards to prior published reports of re-irradiation (re-RT) in patients with recurrent high grade glioma (HGG). A multi-institutional database of 10 academic centers across the United States was created to analyze prognostic outcomes for re-RT for recurrent HGG, which included WHO Grade III and Grade IV tumors.

MATERIALS/METHODS

Patients with HGG who had initially received standard radiotherapy (RT) and were subsequently treated with a course of re-RT at recurrence were included in the study. Factors assessed to delineate a significant association with overall survival (OS) and toxicity included age, KPS, number of relapses, dose, use of bevacizumab (BEV) or temozolomide (TMZ), time from prior RT, histology, RT target, re-RT target> 5cm and extent of resection, and MGMT methylation status. The Kaplan-Meier Method was used to estimate OS. Cox proportional hazards regression models were used to identify factors associated with OS. Toxicity outcomes were assessed using logistic regression. Significance was assumed if p<0.05. Data management and decision management software were used for all analyses.

RESULTS

Between 2001 and 2022, 280 patients from 10 academic institutions were treated with re-RT for diagnosis of recurrent HGG. 133 patients (71.1%) had a histologic glioblastoma (GBM) at the time of re-RT, with the remainder having Grade 3 gliomas. Median dose delivered at re-RT was 47 Gy BED10 (IQR 47 - 53 Gy BED10), with the most common regimen being 35 Gy in 10 fractions. 83 patients (56%) had GTV greater than 5 cm treated with re-RT. 183 patients (79%) received concurrent systemic therapy, including 95 (41%) who received concurrent TMZ and 86 (45%) who received concurrent BEV. Median OS for the entire cohort was 10 months. Increasing dose at re-RT was associated with improved OS (OR 0.80 95% CI 0.67-0.95, p = 0.10 per 10 Gy BED10), as was dose greater than 47 Gy BED10, which is equivalent to 35 Gy in 10 fractions (OR 0.70, 95% CI 0.54-0.91). Concurrent TMZ was also associated with improved OS (OR 0.68, 95% CI 0.46-0.83, p < 0.01). 32/143 (22%) patients evaluable for toxicity experienced Grade 2 or greater adverse radiation effect (ARE). Use of BEV was associated with decreased toxicity (OR 0.45, 95% CI 0.21-0.98, p = 0.05). Dose at re-RT (OR 1.07 per 10 Gy BED10, p = 0.78), a GTV > 5cm (OR 1.39, p = 0.44), and the use of concurrent TMZ (OR 1.90, p = 0.10) were not associated with Grade 2 or greater ARE.

CONCLUSION

Higher dose of re-RT and use of concurrent TMZ led to improved OS in recurrent HGG patients without an associated increased rate of ARE. Use of BEV decreased the likelihood of Grade 2 or greater ARE in the re-RT setting for these recurrent HGG patients.

Bladder-to-bladder metastasis: gallbladder cancer metastasising to the urinary bladder

We report a 48-year-old fit and healthy woman who was incidentally diagnosed to have adenocarcinoma of gallbladder after laparoscopic cholecystectomy. Subsequent imaging showed no evidence of regional or distant spread. She was scheduled for elective laparotomy and resection of gallbladder bed, but during laparotomy frozen section analysis of an incidentally discovered peritoneal deposit confirmed metastasis, so the procedure was abandoned. Thereafter, she received cisplatin and gemcitabine chemotherapy. However, surveillance computed tomography incidentally noted a urinary bladder mass which had not been present before. Transurethral resection of the bladder lesion revealed moderately differentiated adenocarcinoma of urinary bladder. The appearance and immunoprofile of the lesion confirmed metastasis from the primary gallbladder cancer, which has not been documented in the literature to the best of our knowledge. Her disease progressed and she is being challenged with gemcitabine and carboplatin as second-line palliative chemotherapy. She is still alive two years after the initial diagnosis.

Barriers and enablers to the use of venous leg ulcer clinical practice guidelines in Australian primary care: A qualitative study using the theoretical domains framework

BACKGROUND

Venous leg ulcers represent the most common chronic wound problem managed in Australian primary care. Despite the prevalence of the condition, there is an evidence-practice gap in both diagnosis and management of venous leg ulcers.

OBJECTIVE

We used the Theoretical Domains Framework to identify barriers and enablers perceived by primary care practitioners in implementing venous leg ulcer guidelines in clinical practice.

DESIGN

We collected data to explore the experiences of practice nurses and general practitioners related to their use of clinical practice guidelines in management of venous leg ulcers.

SETTING(S)

We recruited participants from primary care settings located in metropolitan and rural areas across Victoria, Australia.

PARTICIPANTS

We recruited general practitioners (15) and practice nurses (20).

METHODS

We conducted 35 semi-structured face-to-face and telephone interviews. Content analysis of health practitioners' statements was performed and barriers to implementing clinical practice guidelines were mapped across the Theoretical Domains Framework theoretical domains.

RESULTS

Six main domains from the Theoretical Domains Framework (Environmental context and resources, Knowledge, Skills, Social influences, Social/Professional Role and Identity and Belief about Capabilities) best explained these barriers and enablers. Many participants were not aware of venous leg ulcer clinical practice guidelines. Those that were aware, stated that finding and accessing guidelines was challenging and most participants relied on other sources of information. Venous leg ulcer management was greatly influenced by professional experience and suggestions from colleagues. Other barriers included busy clinical practice, absence of handheld Doppler ultrasonography, insufficient skills and a lack of confidence related to the use of technology to rule out arterial involvement prior to compression application, a particular skill related to venous leg ulcer management that will impact on healing outcomes.

CONCLUSIONS

We identified a number of barriers and the lack of enablers that influence the uptake of venous leg ulcer clinical practice guidelines in primary care. This paper adds a theoretically sound, systematic approach for understanding and addressing the behaviour change required to improve translation of venous leg ulcer clinical practice guidelines in clinical practice. Tweetable abstract: The need to optimise venous leg ulcer clinical practice guidelines (CPG) has never been greater as the current estimate of health cost is AUD3billion and increasing due to rising epidemics of diabetes and obesity. We found most primary care health practitioners are unaware of CPG and this will impact on health and healing outcomes in Australian primary care.

Barriers and predictors of medication use for childhood ADHD: findings from a UK population-representative cohort

PURPOSE

Little is known about sociodemographic and clinical factors that predict and act as barriers to ADHD medication independently of symptom severity. We examined the proportion of children using medication for ADHD, age of initiation of medication, and predictors of medication use in a population-representative cohort.

METHODS

Data from the Millennium Cohort Study on child ADHD, medication use for ADHD at age 14 (in 2014-2015) and child, parent and sociodemographic variables were collated. Logistic regression models were used to identify factors that predict medication use for ADHD (the main outcome measure), adjusting for symptom severity at age seven.

RESULTS

The weighted prevalence of ADHD was 3.97% (N = 11,708). 45.57% of children with ADHD (N = 305) were taking medication. The median age at initiation was 9 years (range 3-14). Male gender (AOR 3.66, 95% CI 1.75, 7.66) and conduct problems at age seven (AOR 1.24 95% CI 1.04, 1.47) and 14 predicted medication use at age 14 after adjusting for symptom severity.

CONCLUSIONS

Our study is the first to assess predictors of medication whist adjusting for ADHD symptom severity. Girls with ADHD were less likely to be prescribed medication, even when they displayed similar ADHD symptom levels to boys. Conduct problems also predicted medication independently of ADHD symptoms. ADHD may be more often medicated in boys because clinicians may think a prototypical ADHD child is male, and perhaps conduct problems make boys more disruptive in the classroom, leading to boys being more often treated.

Risk factors associated with excessive negative energy balance in commercial United Kingdom dairy herds

This study assessed risk factors associated with excessive negative energy balance (eNEB) in UK dairy cows between April 2006 and March 2015. Blood samples were analysed for β-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA) and glucose. Following removal of all potential duplicate cows, a final dataset of 69,161 unique individual cows was obtained including biochemical results, individual cow and feed data. Generalised linear mixed-effect models and multivariable classification tree-based models showed that individual cow risk factors for eNEB included: (1) days relative to predicted calving date (dry cows); (2) days in milk (lactating cows); (3) body condition score (BCS; lactating cows ≥ BCS 4; OR 2.1); (4) milk yield (around 40 L per day); (5) parity (first lactation heifers; odds ratio [OR] 0.46 compared to older cows during lactation); and (6) chronic inflammatory conditions as assessed by globulin concentrations ≥ 50 g/L (OR 0.79 for cows with evidence of chronic inflammation). There was a higher prevalence during April to October (OR 1.19), and the lowest prevalence was in November. Feeding grass silage and wholecrop (silage made from cereal crops) to dry cows was associated with a reduced prevalence of eNEB, whereas access to grazed grass was associated with a higher prevalence in both the dry period (OR 1.32) and lactation (OR 1.33). Knowledge of the risk factors associated with eNEB in commercial dairy herds assists in both the implementation of herd monitoring programs and reduction of eNEB in dairy herds, with associated reductions in the risk of periparturient diseases and improved dairy cow performance.

Prevalence of excessive negative energy balance in commercial United Kingdom dairy herds

The objectives of this study were to determine the individual animal and herd level prevalence of excessive negative energy balance (eNEB) in commercial UK dairy herds. Between April 2006 and March 2015, blood samples from 84,369 individual cows from 1748 different UK farms were received by a commercial laboratory service specializing in dairy cow nutritional monitoring. Following removal of all potential duplicate cows, the final dataset comprised 69,161 unique individual cows. The prevalence of eNEB was determined using plasma thresholds of β-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA) and glucose. Overall prevalence of subclinical ketosis (SCK) in the first 20 days of lactation was 28.5%, 17.3% and 11.7% using BHB thresholds of 1.0, 1.2 and 1.4 mmol/L respectively. Prevalence of NEFA values ≥0.5 mmol/L in the last 10 days prior to calving was 26.0%, and 40.3% of cows had NEFA values ≥0.7 mmol/L in the first 20 days in milk (DIM). Combining BHB, NEFA and glucose showed that 52.0% of cows had one or more of the three biochemical measures of energy balance outside the respective threshold value in the last 10 days pre-calving, and 75.2% of cows showed a similar biochemical pattern in the first 20 DIM. The median herd prevalence of elevated BHB and/or NEFA was 37.5% in late pregnancy and 59.8% in the first 20 DIM, with substantial herd variation. Using multiple measures for the assessment of energy balance, this study has shown that eNEB affects substantial numbers of UK dairy cows.

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

Factors associated with multiple barriers to access to primary care: an international analysis

Background

Disparities in access to primary care (PC) have been demonstrated within and between health systems. However, few studies have assessed the factors associated with multiple barriers to access occurring along the care-seeking process in different healthcare systems.

Methods

In this secondary analysis of the 2016 Commonwealth Fund International Health Policy Survey of Adults, access was represented through participant responses to questions relating to access barriers either before or after reaching the PC practice in 11 countries (Australia, Canada, France, Germany, Norway, the Netherlands, New Zealand, Sweden, Switzerland, the United Kingdom, and United States). The number of respondents in each country ranged from 1000 to 7000 and the response rates ranged from 11% to 47%. We used multivariable logistic regression models within each of eleven countries to identify disparities in response to the access barriers by age, sex, immigrant status, income and the presence of chronic conditions.

Results

Overall, one in five adults (21%) experienced multiple barriers before reaching PC practices. After reaching care, an average of 16% of adults had two or more barriers. There was a sixfold difference between nations in the experience of these barriers to access. Vulnerable groups experiencing multiple barriers were relatively consistent across countries. People with lower income were more likely to experience multiple barriers, particularly before reaching primary care practices. Respondents with mental health problems and those born outside the country displayed substantial vulnerability in terms of barriers after reaching care.

Conclusion

A greater understanding of the multiple barriers to access to PC across the stages of the care-seeking process may help to inform planning and performance monitoring of disparities in access. Variation across countries may reveal organisational and system drivers of access, and inform efforts to improve access to PC for vulnerable groups. The cumulative nature of these barriers remains to be assessed.

Electronic supplementary material

The online version of this article (10.1186/s12939-018-0740-1) contains supplementary material, which is available to authorized users.

Gaps and barriers in health-care provision for co-morbid diabetes and chronic kidney disease: a cross-sectional study

BACKGROUND

Patients with diabetes and chronic kidney disease (CKD) are a complex subset of the growing number of patients with diabetes, due to multi-morbidity. Gaps between recommended and received care for diabetes and chronic kidney disease (CKD) are evident despite promulgation of guidelines. Here, we document gaps in tertiary health-care, and the commonest patient-reported barriers to health-care, before exploring the association between these gaps and barriers.

METHODS

This cross-sectional study recruited patients with diabetes and CKD (eGFR < 60 mL/min/1.73 m2) across 4 large hospitals. For each patient, questionnaires were completed examining clinical data, recommended care, and patient-reported barriers limiting health-care. Descriptive statistics, subgroup analyses by CKD stage and hospital, and analyses examining the relationship between health-care gaps and barriers were performed.

RESULTS

308 patients, of mean age 66.9 (SD 11.0) years, and mostly male (69.5%) and having type 2 diabetes (88.0%), participated. 49.1% had stage 3, 24.7% stage 4 and 26.3% stage 5 CKD. Gaps between recommended versus received care were evident: 31.9% of patients had an HbA1c ≥ 8%, and 39.3% had a measured blood pressure ≥ 140/90 mmHg. The commonest barriers were poor continuity of care (49.3%), inadequate understanding/education about CKD (43.5%), and feeling unwell (42.6%). However, barriers associated with a failure to receive items of recommended care were inadequate support from family and friends, conflicting advice from and poor communication amongst specialists, the effect of co-morbidities on self-management and feeling unmotivated (all p < 0.05).

CONCLUSIONS

Barriers to health-care varied across CKD stages and hospitals. Barriers associated with a deviation from recommended care were different for different items of care, suggesting that specific interventions targeting each item of care are required.

Assessment of Bias in National Growth-monitoring Data: A Case Study in Zimbabwe

This study assesses the extent to which children under five years of age attending a growth-monitoring program are representative of the population as a whole. Bias in the prevalence of underweight estimated through growth-monitoring is assessed by comparing data from the program with prevalence estimates from the community-based Demographic and Health Surveys of 1988 and 1994. Geographic patterns of attendance at growth-monitoring are also examined through a comparison with census data, and trends in growth-monitoring data are also assessed. Provincial and national estimates of the prevalence of underweight from the two sources were not significantly different in 1988, but significant differences in prevalence estimates were identified in 1994. This suggests that growth-monitoring attendees were less representative of the general population in 1994 than at the start of the study period. The methodology used is transferable elsewhere, since the same data sets exist for many other African countries.

Does father-child conflict mediate the association between fathers' postnatal depressive symptoms and children's adjustment problems at 7 years old?

BACKGROUND

Paternal depressive symptoms are associated with children's emotional and behavioural problems, which may be mediated by negative parenting. But there is no research on the influence of paternal depressive symptoms on children's emotion regulation and limited literature investigating fathers' parenting as a mediator in the pathway between paternal depressive symptoms and children's externalizing and internalizing problems. We aimed to investigate the mediating role of father-child conflict (at 3 years) in the association between postnatal paternal depressive symptoms (at 9 months) and children's emotional and behavioural problems (at 7 years) (aim 1). We also examined whether mediation pathways were more pronounced for boys or for girls (aim 2).

METHOD

Secondary data analysis was conducted on the Millennium Cohort Study, when children were 9 months, 3 years and 7 years old (n = 3520). Main study variables were measured by self-report questionnaires. Fathers completed the Rutter Scale (depressive symptoms) and the Parent-Child Relationship Questionnaire (father-child conflict), while mothers completed the Strengths and Difficulties Questionnaire and the Social Behaviour Questionnaire (child emotional and behavioural problems, emotion regulation). We used structural equation modelling to estimate direct, indirect and total effects of paternal depressive symptoms on child outcomes, mediated by father-child conflict whilst adjusting for relevant covariates (maternal depressive symptoms, child temperament, marital conflict, and socio-economic factors such as poverty indicator and fathers' education level). Multi-group and interaction analysis was then conducted to determine the differential effect by gender of the association between paternal depressive symptoms on child outcomes via father-child conflict.

RESULTS

Father-child conflict mediated the association between paternal depressive symptoms and emotion regulation problems [standardized indirect effect (SIE) 95% confidence interval (CI) -0.03 to -0.01, p < 0.001; standardized total effect (STE) 95% CI -0.05 to -0.01, p < 0.05] (aim 1). Father-child conflict mediated a larger proportion of the effect in boys (SIE 95% CI -0.03 to -0.01, p < 0.001; STE 95% CI -0.05 to 0.00, p = 0.063) than it did in girls (SIE 95% CI -0.02 to -0.01, p < 0.001; STE 95% CI -0.04 to 0.01, p = 0.216) (aim 2).

CONCLUSIONS

Father-child conflict may mediate the association between postnatal paternal depressive symptoms and children's emotion regulation problems. Paternal depressive symptoms and father-child conflict resolution may be potential targets in preventative interventions.

Derivation of the clinical grade human embryonic stem cell line RCe013-A (RC-9)

The human embryonic stem cell line RCe013-A (RC-9) was derived under quality assured compliance with UK regulation, European Union Directives and International guidance for tissue procurement, processing and storage according to Good Manufacturing Practice (GMP) standards. The cell line was derived from a failed to fertilise oocyte voluntarily donated as unsuitable and surplus to fertility requirements following informed consent. RCe013-A (RC-9) shows normal pluripotency marker expression and differentiation to the three germ layers in vitro and in vivo. It has a normal 46XY male karyotype and microsatellite PCR identity, HLA and blood group typing data are available.

Individualised risk assessment for diabetic retinopathy and optimisation of screening intervals: a scientific approach to reducing healthcare costs

Objective

To validate a mathematical algorithm that calculates risk of diabetic retinopathy progression in a diabetic population with UK staging (R0–3; M1) of diabetic retinopathy. To establish the utility of the algorithm to reduce screening frequency in this cohort, while maintaining safety standards.

Research design and methods

The cohort of 9690 diabetic individuals in England, followed for 2 years. The algorithms calculated individual risk for development of preproliferative retinopathy (R2), active proliferative retinopathy (R3A) and diabetic maculopathy (M1) based on clinical data. Screening intervals were determined such that the increase in risk of developing certain stages of retinopathy between screenings was the same for all patients and identical to mean risk in fixed annual screening. Receiver operating characteristic curves were drawn and area under the curve calculated to estimate the prediction capability.

Results

The algorithm predicts the occurrence of the given diabetic retinopathy stages with area under the curve =80% for patients with type II diabetes (CI 0.78 to 0.81). Of the cohort 64% is at less than 5% risk of progression to R2, R3A or M1 within 2 years. By applying a 2 year ceiling to the screening interval, patients with type II diabetes are screened on average every 20 months, which is a 40% reduction in frequency compared with annual screening.

Conclusions

The algorithm reliably identifies patients at high risk of developing advanced stages of diabetic retinopathy, including preproliferative R2, active proliferative R3A and maculopathy M1. Majority of patients have less than 5% risk of progression between stages within a year and a small high-risk group is identified. Screening visit frequency and presumably costs in a diabetic retinopathy screening system can be reduced by 40% by using a 2 year ceiling. Individualised risk assessment with 2 year ceiling on screening intervals may be a pragmatic next step in diabetic retinopathy screening in UK, in that safety is maximised and cost reduced by about 40%.

Obesity prevention in early life: an opportunity to better support the role of Maternal and Child Health Nurses in Australia

Background

Because parents with young children access primary health care services frequently, a key opportunity arises for Maternal and Child Health (MCH) nurses to actively work with families to support healthy infant feeding practices and lifestyle behaviours. However, little is known regarding the extent to which MCH nurses promote obesity prevention practices and how such practices could be better supported.

Methods

This mixed methods study involved a survey of 56 MCH nurses (response rate 84.8 %), 16 of whom participated in semi-structured qualitative interviews. Both components aimed to examine the extent to which nurses addressed healthy infant feeding practices, healthy eating, active play and limiting sedentary behavior during routine consultations with young children 0–5 years. Key factors influencing such practices and how they could be best supported were also investigated. All data were collected from September to December 2013. Survey data were analysed descriptively and triangulated with qualitative interview findings, the analysis of which was guided by grounded theory principles.

Results

Although nurses reported measuring height/length and weight in most consultations, almost one quarter (22.2 %) reported never/rarely using growth charts to identify infants or children at risk of overweight or obesity. This reflected a reluctance to raise the issue of weight with parents and a lack of confidence in how to address it. The majority of nurses reported providing advice on aspects of infant feeding relevant to obesity prevention at most consultations, with around a third (37 %) routinely provided advice on formula preparation. Less than half of nurses routinely promoted active play and only 30 % discussed limiting sedentary behaviour such as TV viewing. Concerns about parental receptiveness and maintaining rapport were key barriers to more effective implementation.

Conclusion

While MCH nurses are well placed to address obesity prevention in early life, there is currently a missed public health opportunity. Improving nurse skills in behaviour change counseling will be key to increasing their confidence in raising sensitive lifestyle issues with parents to better integrate obesity prevention practices into normal MCH service delivery.

Electronic supplementary material

The online version of this article (doi:10.1186/s12912-015-0077-7) contains supplementary material, which is available to authorized users.

Distribution of BoLA-DRB3 allelic frequencies and identification of two new alleles in Iranian buffalo breed

The role of the major histocompatibility complex (MHC) in the immune response makes it an attractive candidate gene for associations with disease resistance and susceptibility. This study describes genetic variability in the BoLA-DRB3 in Iranian buffaloes. Heminested PCR-RFLP method was used to identify the frequency of BoLA-DRB3 alleles. The BoLA-DRB3 locus is highly polymorphic in the study herd (12 alleles). Almost 63.50% of the alleles were accounted for by four alleles (BoLA-DRB3.2 ∗48, ∗20, ∗21, and obe) in Iranian buffalo. The DRB3.2 ∗48 allele frequency (24.20%) was higher than the others. The frequencies of the DRB3.2 ∗20 and DRB3.2 ∗21 are 14.52 and 14.00, respectively, and obe and gbb have a new pattern. Significant distinctions have been found between Iranian buffalo and other cattle breed studied. In the Iranian buffaloes studied alleles associated with resistance to various diseases are found.

The effect of improving cow productivity, fertility, and longevity on the global warming potential of dairy systems

This study compared the environmental impact of a range of dairy production systems in terms of their global warming potential (GWP, expressed as carbon dioxide equivalents, CO(2)-eq.) and associated land use, and explored the efficacy of reducing said impact. Models were developed using the unique data generated from a long-term genetic line × feeding system experiment. Holstein-Friesian cows were selected to represent the UK average for milk fat plus protein production (control line) or were selected for increased milk fat plus protein production (select line). In addition, cows received a low forage diet (50% forage) with no grazing or were on a high forage (75% forage) diet with summer grazing. A Markov chain approach was used to describe the herd structure and help estimate the GWP per year and land required per cow for the 4 alternative systems and the herd average using a partial life cycle assessment. The CO(2)-eq. emissions were expressed per kilogram of energy-corrected milk (ECM) and per hectare of land use, as well as land required per kilogram of ECM. The effects of a phenotypic and genetic standard deviation unit improvement on herd feed utilization efficiency, ECM yield, calving interval length, and incidence of involuntary culling were assessed. The low forage (nongrazing) feeding system with select cows produced the lowest CO(2)-eq. emissions of 1.1 kg/kg of ECM and land use of 0.65 m(2)/kg of ECM but the highest CO(2)-eq. emissions of 16.1t/ha of the production systems studied. Within the herd, an improvement of 1 standard deviation in feed utilization efficiency was the only trait of those studied that would significantly reduce the reliance of the farming system on bought-in synthetic fertilizer and concentrate feed, as well as reduce the average CO(2)-eq. emissions and land use of the herd (both by about 6.5%, of which about 4% would be achievable through selective breeding). Within production systems, reductions in CO(2)-eq. emissions per kilogram of ECM and CO(2)-eq. emissions per hectare were also achievable by an improvement in feed utilization. This study allowed development of models that harness the biological trait variation in the animal to improve the environmental impact of the farming system. Genetic selection for efficient feed use for milk production according to feeding system can bring about reductions in system nutrient requirements, CO(2)-eq. emissions, and land use per unit product.