Impact of COVID-19 on the veteran population: evidence from the Trends in Scottish Veterans Health study

INTRODUCTION

There have been few epidemiological studies on the impact of the SARS-CoV-2 (COVID-19) pandemic on the veteran population, other than on specific aspects such as mental health, and none in the UK. We used data from the Trends in Scottish Veterans Health cohort to explore the risk of hospitalisation and death associated with COVID-19 in veterans resident in Scotland in comparison with matched non-veterans.

METHODS

Retrospective cohort study of 71 000 veterans and a comparison group of 230 000 non-veterans matched for age, sex and geography, using Cox proportional hazard analysis to explore the risk of hospitalisation with COVID-19 and COVID-19-associated death overall and by birth cohort, sex and length of military service.

RESULTS

Between 1 January 2020 and 31 December 2021, 564 (0.79%) veterans had been hospitalised with COVID-19 compared with 1728 (0.75%) non-veterans. The Cox model showed no significant difference overall, HR 0.99, 95% CIs 0.90 to 1.11, p=0.800. Subgroup analysis showed increased risk in older, short-serving (<20 weeks) Early Service Leavers (ESL). There was no overall difference in COVID-19-associated deaths, HR 0.99, 95% CI 0.79 to 1.23, p=0.993, but subgroup analysis showed a non-significant reduced risk of death in veterans aged 61-70 years, and a 38% higher risk in veterans aged over 70 years which almost reached statistical significance, p=0.054. This was only partially explained by socioeconomic factors and common comorbidities, although we had no data on domestic circumstances or care home residence.

CONCLUSIONS

Overall, military service was not a risk factor for either hospitalisation or death associated with COVID-19. Older ESLs were at increased risk compared with non-veterans, but military service is unlikely to have been causal. The risk of death was increased in the oldest veterans and further studies are needed to explain this once census data become available for linkage.

Increased risk of lower limb osteoarthritis among former professional soccer (football) players

BACKGROUND

Soccer is a high-speed contact sport with risk of injury. Despite long-standing concern, evidence to date remains inconsistent as to the association between playing professional-level soccer and lifelong musculoskeletal consequences.

AIMS

The objectives were to assess risk of osteoarthritis in former professional soccer players compared to matched general population controls, and subsequently assess associated musculoskeletal disorders which may contribute to, or result from, osteoarthritis-specifically meniscal injury and joint replacement.

METHODS

We conducted a retrospective cohort study using national electronic health records (EHRs) on a cohort of 7676 former professional soccer players aged 40 or over at recruitment, matched on year of birth, sex (all male) and socio-economic status with 23 028 general population controls. Outcomes of interest were obtained by utilizing individual-level record linkage to EHRs from general hospital inpatient and day-case admissions.

RESULTS

Compared to controls, former soccer players showed a greater risk of hospital admission for osteoarthritis (hazard ratio [HR] 3.01; 95% confidence interval [CI] 2.80-3.25; P < 0.001). This increased risk appeared age dependant, normalizing over age 80 years and reflective of increased risk of lower limb osteoarthritis. Further, risk of hospital admissions for meniscal injury (HR 2.73; 95% CI 2.42-3.08; P < 0.001) and joint replacement (HR 2.82; 95% CI 2.23-3.57; P < 0.001) were greater among former soccer players.

CONCLUSIONS

We report an increased risk of lower limb osteoarthritis in former soccer players when compared with matched population controls. The results of this research add data in support of lower limb osteoarthritis among former soccer players representing a potential industrial injury.

Dementia in Scottish military veterans: early evidence from a retrospective cohort study

BACKGROUND

Few studies have examined whether UK military veterans are at an increased risk of dementia. We explored the risk of dementia in Scottish military veterans aged up to 73 years in comparison with people who have never served.

METHODS

Retrospective cohort study of 78 000 veterans and 253 000 people with no record of service, matched for age, sex and area of residence, with up to 37 years follow-up, using Cox proportional hazard analysis to compare risk of dementia in veterans and non-veterans, overall and by subgroup.

RESULTS

Dementia was recorded in 0.2% of both veterans and non-veterans overall, Cox proportional hazard ratio 0.98, 95% confidence interval (CI) 0.82-1.19, p = 0.879 (landmark age: 50 years), with no difference for men but increased risk in veteran women and Early Service Leavers. Post-traumatic stress disorder (PTSD) was associated with a higher risk of dementia in both veterans and non-veterans, although possibly to a lesser degree in veterans. A history of mood disorder was strongly associated with developing dementia, greater in veterans than in non-veterans, odds ratio 1.54, 95% CI 1.01-2.35, p = 0.045.

CONCLUSIONS

There was no evidence to suggest that military service increased the risk of dementia, although this may change as the cohort ages. The well-documented association with PTSD shows no evidence of being stronger in veterans; by contrast, the association of mood disorder with dementia is much stronger in veterans. Healthcare providers should carefully assess the cognitive status of older veterans presenting with depressive illness in order to identify early dementia and ensure optimum management.

Hip and knee replacement as a proxy measure for lower limb osteoarthritis in Scottish military veterans

INTRODUCTION

Physical activity is an important component of military training. Although injuries and musculoskeletal disorders are the most common cause of medical retirement from the Armed Forces, the long-term risk of lower limb osteoarthritis in veterans is unknown. We used data on hip and knee replacement in Scottish military veterans as a proxy measure.

METHODS

Retrospective cohort study of 78 000 veterans born between 1945 and 1995 and a comparison group of 253 000 non-veterans, matched for age, sex and area of residence, followed up for up to 37 years, using survival analysis to examine the risk of hip and knee replacement.

RESULTS

Veterans were significantly less likely to undergo hip replacement than non-veterans, Cox proportional HR 0.87, 95% CI 0.80 to 0.95, p<0.001. There was no significant difference between veterans and non-veterans in respect of knee replacement, HR 1.02, 95% CI 0.94 to 1.11, p=0.643, and there was no difference in the ages at which veterans and non-veterans underwent joint replacement. People who had served for longest in the military had similar risk to those with the shortest service.

CONCLUSIONS

Based on the likelihood of undergoing joint replacement surgery in later life, we found no evidence of a positive association between military service and an increased risk of lower limb osteoarthritis.

Risk factors for mental ill health in UK Army personnel: an overview

Women in the UK military are more commonly diagnosed with a mental health disorder than men, but the reasons for this difference are not fully understood. This literature review identifies the risk factors for mental ill health in military personnel before serving, during service and as a veteran. The interaction of risk factors is complex and, in some cases, may be synergistic, such as experiencing adverse events in childhood and exposure to combat. Identification of risk factors allows further research to better understand differences between men and women, and the impact of these risk factors on army personnel. In turn this will inform better preventive strategies, which could be targeted at the primary, secondary or tertiary levels.

Age at entry to UK military service and long-term mental health

INTRODUCTION

It has been suggested that 'junior entry' to the UK Armed Forces (prior to age 17.5 years) increases the risk of adverse mental health outcomes. We used data from a large cohort of veterans to examine long-term mental health outcomes in veterans by age at entry to the UK Armed Forces, compared with non-veterans.

METHODS

Retrospective cohort study of 78 157 veterans in Scotland, born between 1945 and 1995 and and 252 637 matched non-veterans, with up to 37 years follow-up, using Cox proportional hazard models to examine the association between veteran status and cumulative risk of major mental health disorder, stratified by birth cohort, and age at recruitment for the veterans.

RESULTS

The risk of mental health disorder in the veterans increased with age at entry, ranging from HR 1.12, 95% CI 1.06 to 1.18, p<0.001 for junior entrants to HR 1.37, 95% CI 1.27 to 1.80, p<0.001 for those aged 20-25 years at entry. The pattern was most marked for veterans born before 1960, and age at recruitment had little impact in recent birth cohorts. Post-traumatic stress disorder accounted for most of the observed differences. Younger age at recruitment was associated with longer service, median 7.4 years (IQR 3.0-14.7) compared with 5.6 years (IQR 2.1-11.7) for entrants aged 20-25 years.

CONCLUSION

We found no evidence that early recruitment is associated with adverse impact on long-term mental health. Paradoxically, it was veterans who entered service at age 20-25 years who demonstrated increased risk, although this attenuated in more recent birth cohorts.

Postservice lower limb amputation in Scottish military veterans

INTRODUCTION

Recent attention has focused on veterans who have lost limbs in conflict, but the number of UK veterans who lose limbs to disease is unknown. We used data from the Trends in Scottish Veterans' Health study to explore postservice lower limb amputation.

METHODS

We carried out a retrospective cohort study of 78 000 veterans and 253 000 non-veterans born between 1945 and 1995, matched for age, sex and area of residence. We used survival analysis to examine the risk of amputation in veterans compared with non-veterans, and explored associations with antecedent disease.

RESULTS

We found no difference between veterans and non-veterans in the risk of lower limb amputation, which was recorded in 145 (0.19%) veterans and 464 (0.18%) non-veterans (Cox proportional hazard ratio (HR) 1.00, 95% CIs 0.82 to 1.20, p=0.961). Peripheral arterial disease was recorded in two-thirds of both veteran and non-veteran amputees, and type 2 diabetes in 41% of veterans and 33% of non-veterans, with a dual diagnosis in 32% of veterans and 26% of non-veterans. Trauma was an infrequent cause of amputation.

CONCLUSIONS

Although in later life veterans are no more likely to lose a limb to disease than non-veterans, the number so affected greatly outweighs those who have lost limbs in conflict. The high public profile of conflict-related limb loss risks eclipsing the needs of veterans with disease-related loss. Support for ageing veterans who have lost limbs due to disease will require planning with the same care as that afforded to the victims of conflict if inequalities are to be avoided.

Peripheral arterial disease in Scottish military veterans: a retrospective cohort study of 57 000 veterans and 173 000 matched non-veterans

BACKGROUND

While traumatic limb loss in military personnel is widely known, the threat posed by peripheral arterial disease (PAD) in those who have served is less well recognized. The aim of our study was to examine the risk of PAD in a Scotland-wide cohort of veterans who served between 1960 and 2012.

METHODS

Retrospective 30-year cohort study of 56 205 veterans born 1945-85, and 172 741 non-veterans, matched for age, sex and area of residence, using Cox proportional hazard models to examine the association between veteran status, birth cohort, length of service and risk of PAD leading to hospitalization or death.

RESULTS

Overall, veterans were at increased risk of PAD compared with non-veterans, unadjusted hazard ratio (HR) = 1.46, 95% confidence intervals (CI): 1.33-1.60, P < 0.001. The highest risk was in veterans born between 1950 and 1954, HR = 1.76, 95% CI: 1.50-2.07, P < 0.001, and in those with the shortest service (early service leavers), HR = 1.84, 95% CI: 1.49-2.27, P < 0.001.

CONCLUSIONS

The findings provide evidence for a hidden burden of life- and limb-threatening PAD in older veterans and are consistent with the higher rates of military smoking which have been reported previously. The study emphasizes the need for vascular preventive measures in this group.

Healthy workers or less healthy leavers? Mortality in military veterans

BACKGROUND

The 'healthy worker effect' predicts that longer employment is positively associated with reduced mortality, but few studies have examined mortality in military veterans irrespective of exposure to conflict.

AIMS

To examine mortality in a large national cohort of Scottish veterans by length of service.

METHODS

Retrospective cohort study comparing survival in up to 30-year follow-up among 57 000 veterans and 173 000 people with no record of service, matched for age, sex and area of residence, who were born between 1945 and 1985. We compared antecedent diagnoses in the two groups to provide information on probable risk factors.

RESULTS

By the end of follow-up, 3520 (6%) veterans had died, compared with 10 947 (6%) non-veterans. Cox proportional hazard analysis confirmed no significant difference overall unadjusted or after adjusting for deprivation. On subgroup analysis, those who left prematurely (early service leavers) were at significantly increased risk of death (hazard ratio (HR) 1.16, 95% confidence interval (CI) 1.09-1.24, P < 0.001), although the increase became non-significant after adjusting for socioeconomic status (HR 1.05, 95% CI 0.99-1.12). Longer-serving veterans were at significantly lower risk of death than non-veterans; the risk decreased both with length of service and in more recent birth cohorts. Smoking-related disease was the greatest contributor to increased mortality in early leavers.

CONCLUSIONS

Among longer-serving veterans, there was evidence of a HWE partly attributable to selective attrition of early service leavers, but birth cohort analysis suggests improvements over time which may also reflect a causal effect of improved in-service health promotion.

In utero exposure to antidepressant medication and neonatal and child outcomes: a systematic review

OBJECTIVE

The aim of this study is to systematically review published studies, reporting outcomes to offspring following in utero exposure to antidepressant medications, which used an untreated depressed comparison group.

METHODS

OVID, Scopus, EBSCO Collections, the Cochrane Library and Web of Science databases were searched for relevant publications published between January 1950 and May 2018 and a total of 188 potentially eligible studies were identified.

RESULTS

Following review, 16 primary studies were eligible for inclusion. Antidepressant exposure was associated with an increased risk of lower gestational age, preterm birth, but not low birthweight or being small for gestational age compared to untreated depression. There is some evidence that congenital defects are associated with antidepressant use, particularly between cardiac defects and paroxetine use. There is conflicting evidence regarding neurodevelopment in offspring, with some reports of increased incidence of autistic spectrum disorders and depression, but also reports of no problems when measuring emotional symptoms, peer problems, conduct problems and hyperactivity-inattention scores.

CONCLUSION

When compared with an untreated depressed group, antidepressant exposure was associated with adverse outcomes at birth, while there is insufficient data to determine whether the association between antidepressants and congenital defects or developmental disorders is a true association. However, although we compared treated vs. untreated depression there still may be residual confounding as an untreated depressed group is likely to have less severe depression.

P3823Body mass index or waist and hip circumference as predictors of outcome in the UK biobank

Background

Controversies exist about the relationship between body habitus and mortality, especially for patients with cardiovascular disease.

Purpose

We evaluated the relations between different anthropometric indices and mortality amongst participants with and without cardiovascular (CV) risk factors, or established CV disease (stroke, myocardial infarction and/or heart failure), enrolled in the UK Biobank.

Methods

The UK Biobank is a large prospective study which, between 2006 and 2010, enrolled 502,620 participants aged 38–73 years. Participants filled questionnaires and had a medical history recorded, physical measurements done and biological samples taken. The UK Biobank is routinely linked to national death registries and updated on a quarterly basis. Data on death were coded according to the International Classification of Diseases, 10th Revision (ICD-10). The primary end-point was all-cause mortality (ACM) across three subgroups of men and women: those with, or without, one or more CV risk factors (smoking, diabetes and/or hypertension), and those with CV disease (history of stroke, myocardial infarction and/or heart failure) at recruitment. Presence, or absence, of CV risk factors and diagnoses of CV disease were self-reported by participants at enrolment. Associations between anthropometric indices (body mass index (BMI), waist circumference (WC), waist to hip ratio (WHiR), and waist to height ratio (WHeR)) and the risk of all-cause mortality were analysed using Cox regression models.

Results

After excluding those with history of cancer at baseline (n=45,222), 453,046 participants were included (median age: 58 (interquartile range: 50 - 63) years; 53% women), of whom 150,732 had at least one CV risk factor, and 17,884 established CV disease.

During a median follow-up of 5 years, 6,319 participants died. Baseline BMI had a U-shaped relationship with ACM, with higher nadir-values for those with CV risk factors or CV disease, for both sexes (figure). WC, WHiR and WHeR (measures of central distribution of body fat) had more linear associations with ACM, regardless of CV risk factors, CV disease and sex.

Conclusions

For adults with or without CV risk factors or established CV disease, measures of central distribution of body fat are more strongly and more linearly associated with ACM than BMI. WC, or WHiR, rather than BMI, appear to be more appropriate variables for risk stratification.

The association between driving time and unhealthy lifestyles: a cross-sectional, general population study of 386 493 UK Biobank participants

BACKGROUND

Driving is a common type of sedentary behaviour; an independent risk factor for poor health. The study explores whether driving is also associated with other unhealthy lifestyle factors.

METHODS

In a cross-sectional study of UK Biobank participants, driving time was treated as an ordinal variable and other lifestyle factors dichotomized into low/high risk based on guidelines. The associations were explored using chi-square tests for trend and binary logistic regression.

RESULTS

Of the 386 493 participants who drove, 153 717 (39.8%) drove <1 h/day; 140 140 (36.3%) 1 h/day; 60 973 (15.8%) 2 h/day; and 31 663 (8.2%) ≥3 h/day. Following adjustment for potential confounders, driving ≥3 h/day was associated with being overweight/obese (OR = 1.74, 95% CI: 1.64-1.85), smoking (OR = 1.48, 95% CI: 1.37-1.63), insufficient sleep (1.70, 95% CI: 1.61-1.80), low fruit/vegetable intake (OR = 1.26, 95% CI: 1.18-1.35) and low physical activity (OR = 1.05, 95% CI: 1.00-1.11), with dose relationships for the first three, but was not associated with higher alcohol consumption (OR = 0.94, 95% CI: 0.87-1.02).

CONCLUSIONS

Sedentary behaviour, such as driving, is known to have an independent association with adverse health outcomes. It may have additional impact mediated through its effect on other aspects of lifestyle. People with long driving times are at higher risk and might benefit from targeted interventions.

The lifetime prevalence of hospitalised head injury in Scottish prisons: A population study

Background

There is mounting evidence that associates brain injury and offending behaviour, and there is a need to understand the epidemiology of head injury in prisoners in order to plan interventions to reduce associated disability and risk of reoffending. This is the first study to determine the lifetime prevalence of hospitalised head injury (HHI) in a national population of current prison inmates. In addition characteristics of prisoners with HHI and were compared to prisoners without HHI to discover whether those with HI differed demographically.

Methods

Whole life hospital records of everyone aged 35 years or younger and resident in a prison in Scotland on a census date in 2015 were electronically linked via their unique NHS identifier and checked for ICD-9 and 10 codes for head injury. Using a case-control design, these data were compared with a sample from the general population matched 3:1 for age, gender and area-based social deprivation. Comparison of demographic variables was made between prisoners with and without HHI.

Results

HHI was found in 24.7% (1,080/4,374) of prisoners and was significantly more prevalent than found in the matched general population sample (18.2%; 2394/13122; OR 2.10; 95%CI 1.87, 2.16). The prevalence of HHI in prisoners and controls was similar with the exception of a higher risk of HHI in prisoners in lower deprivation quintiles. Having three or more HHI was more common in prisoners (OR 3.04; 95%CI 2.33, 3.97) as were HHI with ICD codes for intracranial injuries (OR 1.81; 95% CI 1.54, 2.11), suggesting that more severe HHI is more prevalent in prisoners than the general population. The distributions within demographic variables and the characteristics of HHI admissions in prisoners with and without a history of HHI were similar.

Conclusion

Prisoners in Scotland aged 35 years or younger have a higher lifetime prevalence of HHI than the general population and are more likely to have had repeated HI or intracranial injuries. Further work is required to elucidate the correspondence between self-report of HI and hospitalised records and to ascertain persisting effects of HI in prisoners and the need for services to reduce associated disability and risk of reoffending.

Tobacco exposure and sleep disturbance in 498 208 UK Biobank participants

Background

The prevalence of sleep disturbance is high and increasing. The study investigated whether active, former and passive smoking were associated with sleep disturbance.

Methods

This cross-sectional study used data from the UK Biobank: a cohort study of 502 655 participants, of whom 498 208 provided self-reported data on smoking and sleep characteristics. Multivariable multinomial and logistic regression models were used to examine the associations between smoking and sleep disturbance.

Results

Long-sleep duration (>9 h) was more common among current smokers [odds ratio (OR): 1.47; 95% confidence interval (CI): 1.17-1.85; probability value (P) = 0.001] than never smokers, especially heavy (>20/day) smokers (OR: 2.85; 95% CI: 1.66-4.89; P < 0.001). Former heavy (>20/day) smokers were also more likely to report short (<6 h) sleep duration (OR: 1.41; 95% CI: 1.25-1.60; P < 0.001), long-sleep duration (OR: 1.99; 95% CI: 1.47-2.71; P < 0.001) and sleeplessness (OR: 1.47; 95% CI: 1.38-1.57; P < 0.001) than never smokers. Among never smokers, those who lived with more than one smoker had higher odds of long-sleep duration than those not cohabitating with a smoker (OR: 2.71; 95% CI: 1.26-5.82; P = 0.011).

Conclusions

Active and passive exposure to high levels of tobacco smoke are associated with sleep disturbance. Existing global tobacco control interventions need to be enforced.

Adiposity among 132 479 UK Biobank participants; contribution of sugar intake vs other macronutrients

Background

Policy makers are being encouraged to specifically target sugar intake in order to combat obesity. We examined the extent to which sugar, relative to other macronutrients, was associated with adiposity.

Methods

We used baseline data from UK Biobank to examine the associations between energy intake (total and individual macronutrients) and adiposity [body mass index (BMI), percentage body fat and waist circumference]. Linear regression models were conducted univariately and adjusted for age, sex, ethnicity and physical activity.

Results

Among 132 479 participants, 66.3% of men and 51.8% of women were overweight/obese. There was a weak correlation (r = 0.24) between energy from sugar and fat; 13% of those in the highest quintile for sugar were in the lowest for fat, and vice versa. Compared with normal BMI, obese participants had 11.5% higher total energy intake and 14.6%, 13.8%, 9.5% and 4.7% higher intake from fat, protein, starch and sugar, respectively. Hence, the proportion of energy derived from fat was higher (34.3% vs 33.4%, P < 0.001) but from sugar was lower (22.0% vs 23.4%, P < 0.001). BMI was more strongly associated with total energy [coefficient 2.47, 95% confidence interval (CI) 2.36-2.55] and energy from fat (coefficient 1.96, 95% CI 1.91-2.06) than sugar (coefficient 0.48, 95% CI 0.41-0.55). The latter became negative after adjustment for total energy.

Conclusions

Fat is the largest contributor to overall energy. The proportion of energy from fat in the diet, but not sugar, is higher among overweight/obese individuals. Focusing public health messages on sugar may mislead on the need to reduce fat and overall energy consumption.

Men across a range of ethnicities have a higher prevalence of diabetes: findings from a cross-sectional study of 500 000 UK Biobank participants

AIMS

Studies show that white men have a higher prevalence of Type 2 diabetes mellitus than women at a given age and BMI, but equivalent standardized data for other ethnic groups in the UK are sparse.

METHODS

This cross-sectional study analysed UK Biobank data from 489 079 participants to compare the prevalence of diabetes mellitus across four major ethnic groups including: 471 700 (96.4%) white, 7871 (1.6%) South Asian, 7974 (1.6%) black and 1534 (0.3%) Chinese participants, before and after standardizing for age, socio-economic status (SES), BMI and lifestyle factors including physical activity, TV viewing, fruit and vegetable intake, processed meat, red meat, oily fish, alcohol intake and smoking. A subgroup analysis of South Asians was also undertaken.

RESULTS

Crude diabetes prevalence was higher in men across all four ethnicities. After standardizing for age, SES, BMI and lifestyle factors, a significant sex difference in diabetes prevalence persisted in white (men 6.0% vs. women 3.6%), South Asian (21.0% vs. 13.8%) and black individuals (13.3% vs. 9.7%) (P < 0.0001); there was a non-significant difference between Chinese men and women (7.1% vs. 5.5%) (P = 0.211). Sex differences persisted across South Asian subgroups.

CONCLUSIONS

Men across a range of major ethnic groups including white, South Asian and black, have a higher prevalence of diabetes compared with women of similar age, BMI, SES and lifestyle in the UK.

Association between grip strength and diabetes prevalence in black, South-Asian, and white European ethnic groups: a cross-sectional analysis of 418 656 participants in the UK Biobank study

AIMS

To quantify the extent to which ethnic differences in muscular strength might account for the substantially higher prevalence of diabetes in black and South-Asian compared with white European adults.

METHODS

This cross-sectional study used baseline data from the UK Biobank study on 418 656 white European, black and South-Asian participants, aged 40-69 years, who had complete data on diabetes status and hand-grip strength. Associations between hand-grip strength and diabetes were assessed using logistic regression and were adjusted for potential confounding factors.

RESULTS

Lower grip strength was associated with higher prevalence of diabetes, independent of confounding factors, across all ethnicities in both men and women. Diabetes prevalence was approximately three- to fourfold higher in South-Asian and two- to threefold higher in black participants compared with white European participants across all levels of grip strength, but grip strength in South-Asian men and women was ~ 5-6 kg lower than in the other ethnic groups. Thus, the attributable risk for diabetes associated with low grip strength was substantially higher in South-Asian participants (3.9 and 4.2 cases per 100 men and women, respectively) than in white participants (2.0 and 0.6 cases per 100 men and women, respectively). Attributable risk associated with low grip strength was also high in black men (4.3 cases) but not in black women (0.4 cases).

CONCLUSIONS

Low strength is associated with a disproportionately large number of diabetes cases in South-Asian men and women and in black men. Trials are needed to determine whether interventions to improve strength in these groups could help reduce ethnic inequalities in diabetes prevalence.

Dietary fat and total energy intake modifies the association of genetic profile risk score on obesity: evidence from 48 170 UK Biobank participants

BACKGROUND

Obesity is a multifactorial condition influenced by both genetics and lifestyle. The aim of this study was to investigate whether the association between a validated genetic profile risk score for obesity (GPRS-obesity) and body mass index (BMI) or waist circumference (WC) was modified by macronutrient intake in a large general population study.

METHODS

This study included cross-sectional data from 48 170 white European adults, aged 37-73 years, participating in the UK Biobank. Interactions between GPRS-obesity and macronutrient intake (including total energy, protein, fat, carbohydrate and dietary fibre intake) and its effects on BMI and WC were investigated.

RESULTS

The 93-single-nucleotide polymorphism (SNP) GPRS was associated with a higher BMI (β: 0.57 kg m^-2 per s.d. increase in GPRS (95% confidence interval: 0.53-0.60); P=1.9 × 10^-183) independent of major confounding factors. There was a significant interaction between GPRS and total fat intake (P_{(interaction)}=0.007). Among high-fat-intake individuals, BMI was higher by 0.60 (0.52, 0.67) kg m^-2 per s.d. increase in GPRS-obesity; the change in BMI with GPRS was lower among low-fat-intake individuals (β: 0.50 (0.44, 0.57) kg m^-2). Significant interactions with similar patterns were observed for saturated fat intake (high β: 0.66 (0.59, 0.73) versus low β: 0.49 (0.42, 0.55) kg m^-2, P_{(interaction)}=2 × 10^-4) and for total energy intake (high β: 0.58 (0.51, 0.64) versus low β: 0.49 (0.42, 0.56) kg m^-2, P_{(interaction)}=0.019), but not for protein intake, carbohydrate intake and fibre intake (P_{(interaction)} >0.05). The findings were broadly similar using WC as the outcome.

CONCLUSIONS

These data suggest that the benefits of reducing the intake of fats and total energy intake may be more important in individuals with high genetic risk for obesity.

Chronic obstructive pulmonary disease in Scottish military veterans

Introduction

Smoking is a major risk factor for chronic obstructive pulmonary disease (COPD). Serving military personnel have previously been shown to be more likely to smoke, and to smoke more heavily, than civilians, but there is no clear consensus as to whether in later life, as veterans, they experience a higher prevalence and mortality from COPD than do non-veterans. We examined the risk of COPD in Scottish veterans and assessed the impact of changes in military smoking.

Methods

Retrospective 30-year cohort study of 56 205 veterans born 1945–1985, and 172 741 people with no record of military service, matched for age, sex and area of residence, using Cox proportional hazard models to examine the association between veteran status, birth cohort, length of service and risk of COPD resulting in hospitalisation or death.

Results

There were 1966 (3.52%) cases of COPD meeting the definition in veterans, compared with 5434 (3.19%) in non-veterans. The difference was statistically significant (p=0.001) in the unadjusted model although it became non-significant after adjusting for deprivation. The highest risk was seen in the oldest (1945–1949) birth cohort and in veterans with the shortest service (Early Service Leavers). The risk was significantly reduced in veterans born from 1960, and in those with over 12 years' service.

Conclusions

Our findings are consistent with falling rates of military smoking since the 1960s, and with the reduction in smoking with longer service. The oldest veterans, and those with the shortest service, are least likely to have benefited from this, as reflected in their higher risk for COPD.

Exposure to tobacco smoke in utero or during early childhood and risk of hypomania: Prospective birth cohort study

OBJECTIVES

Using data from a prospective birth cohort, we aimed to test for an association between exposure to tobacco smoke in utero or during early development and the experience of hypomania assessed in young adulthood.

METHODS

We used data on 2957 participants from a large birth cohort (Avon longitudinal study of parents and children [ALSPAC]). The primary outcome of interest was hypomania, and the secondary outcome was "hypomania plus previous psychotic experiences (PE)". Maternally-reported smoking during pregnancy, paternal smoking and exposure to environmental tobacco smoke (ETS) in childhood were the exposures of interest. Multivariable logistic regression was used and estimates of association were adjusted for socio-economic, lifestyle and obstetric factors.

RESULTS

There was weak evidence of an association between exposure to maternal smoking in utero and lifetime hypomania. However, there was a strong association of maternal smoking during pregnancy within the sub-group of individuals with hypomania who had also experienced psychotic symptoms (OR=3.45; 95% CI: 1.49-7.98; P=0.004). There was no association between paternal smoking, or exposure to ETS during childhood, and hypomania outcomes.

CONCLUSIONS

Exposure to smoking in utero may be a risk factor for more severe forms of psychopathology on the mood-psychosis spectrum, rather than DSM-defined bipolar disorder.

Early adoption of screening and the changing pattern of cervical cancer in UK military women: evidence from the Scottish Veterans Health Study

OBJECTIVE

To examine the risk of cervical cancer in a large national cohort of military veteran women followed up for up to 30 years.

METHODS

Retrospective cohort study of 5235 veteran women born between 1945 and 1985, and 20 703 women with no record of service matched for age and area of residence, using Cox proportional hazard models to compare the overall risk of cervical cancer and by year of birth.

RESULTS

During the follow-up period 1981-2012, there were 18 (0.34%) cases of cervical cancer in the veteran women compared with 81 (0.39%) in the non-veterans. The difference was not statistically significant overall (adjusted HR 0.95, 95% CI 0.57 to 1.59). When analysed by the year of birth, veteran women born in 1958 and earlier had a non-significantly higher risk than non-veterans (adjusted HR 1.24, 95% CI 0.68 to 2.26), while veteran women born after 1958 had a non-significant reduction in risk (adjusted HR 0.51, 95% CI 0.18 to 1.44).

CONCLUSIONS

Women born after 1958 who have served in the Armed Forces are at reduced risk of cervical cancer compared with women who have never served, and compared with older veteran women. Small numbers of cases precluded statistical significance. The change in risk pattern in veteran women coincided with the introduction of cervical screening in the Armed Forces, which predated the UK national programme, and provides evidence for the long-term effectiveness of the Armed Forces' sexual health strategy. The impact of recent changes in the screening age, and of human papillomavirus immunisation, should be monitored in the future.

Cognitive function and lifetime features of depression and bipolar disorder in a large population sample: Cross-sectional study of 143,828 UK Biobank participants

BACKGROUND

This study investigated differences in cognitive performance between middle-aged adults with and without a lifetime history of mood disorder features, adjusting for a range of potential confounders.

METHODS

Cross-sectional analysis of baseline data from the UK Biobank cohort. Adults aged 40-69 (n=143,828) were assessed using measures of reasoning, reaction time and memory. Self-reported data on lifetime features of major depression and bipolar disorder were used to construct groups for comparison against controls. Regression models examined the association between mood disorder classification and cognitive performance, adjusting for sociodemographic, lifestyle and clinical confounders.

RESULTS

Inverse associations between lifetime history of bipolar or severe recurrent depression features and cognitive performance were attenuated or reversed after adjusting for confounders, including psychotropic medication use and current depressive symptoms. Participants with a lifetime history of single episode or moderate recurrent depression features outperformed controls to a small (but statistically significant) degree, independent of adjustment for confounders. There was a significant interaction between use of psychotropic medication and lifetime mood disorder features, with reduced cognitive performance observed in participants taking psychotropic medication.

CONCLUSIONS

In this general population sample of adults in middle age, lifetime features of recurrent depression or bipolar disorder were only associated with cognitive impairment within unadjusted analyses. These findings underscore the importance of adjusting for potential confounders when investigating mood disorder-related cognitive function.

Association between salivary cotinine and cardiovascular biomarkers among nonsmokers and current smokers: cross-sectional study of 10,081 participants

OBJECTIVE

Both active smoking and exposure to secondhand smoke (SHS) are associated with cardiovascular disease, but sidestream smoke contains higher levels of small particles and toxic gases than mainstream smoke. The relationship between the concentration of cotinine and a number of cardiovascular biomarkers among nonsmokers and active smokers was examined.

METHODS

A cross-sectional study using the Scottish Health Surveys conducted between 1998 and 2010 was undertaken. Inclusion was restricted to participants aged ≥16 years who had provided saliva and blood samples. Uni- and multivariate regression models were used to examine the relationships between the concentration of cotinine and C-reactive protein (CRP), high-density lipoprotein (HDL) cholesterol, and fibrinogen concentrations, as well as total:HDL cholesterol ratios.

RESULTS

Of the 10,018 eligible participants, 7,345 (73.3%) were confirmed to be nonsmokers (cotinine <15.0 ng/mL) and 2,673 (26.7%) were confirmed to be current smokers (cotinine ≥15.0 ng/mL). CRP and total:HDL cholesterol increased, and HDL cholesterol decreased, with increasing cotinine concentration across nonsmokers and smokers (all p < .001). However, there were step changes at the interface, whereby nonsmokers with a high exposure to SHS had lower concentrations of cotinine than light active smokers but comparable concentrations of CRP (p = .709), HDL cholesterol (p = .931), and total:HDL cholesterol (p = .405). Fibrinogen concentrations were significantly raised in moderate and heavy active smokers only (both p < .001).

CONCLUSION

Exposure to SHS is associated with disproportionately higher biomarkers of cardiovascular risk compared with active smoking. Protection from exposure to SHS should be a public health priority.

Association between body mass index and mental health among Scottish adult population: a cross-sectional study of 37,272 participants

BACKGROUND

The evidence is conflicting as to whether body mass index (BMI) is associated with mental health and, if so, to what extent it varies by sex and age. We studied mental health across the full spectrum of BMI among the general population, and conducted subgroup analyses by sex and age.

METHOD

We undertook a cross-sectional study of a representative sample of the Scottish adult population. The Scottish Health Survey provided data on mental health, measured by the General Health Questionnaire-12 (GHQ), BMI, demographic and life-style information. Good mental health was defined as a GHQ score <4, and poor mental health as a GHQ score ⩾4. Logistic regression models were applied.

RESULTS

Of the 37 272 participants, 5739 (15.4%) had poor mental health. Overall, overweight participants had better mental health than the normal-weight group [adjusted odds ratio (OR) 0.93, 95% confidence interval (CI) 0.87-0.99, p = 0.049], and individuals who were underweight, class II or class III obese had poorer mental health (class III obese group: adjusted OR 1.26, 95% CI 1.05-1.51, p = 0.013). There were significant interactions of BMI with sex (p = 0.013) and with age (p < 0.001). Being overweight was associated with significantly better mental health in middle-aged men only. In contrast, being underweight at all ages or obese at a young age was associated with significantly poorer mental health in women only.

CONCLUSIONS

The adverse associations between adiposity and mental health are specific to women. Underweight women and young women who are obese have poorer mental health. In contrast, middle-aged overweight men have better mental health.

Effects of three whole-farmlet management systems on Merino ewe fat scores and reproduction

As part of the Cicerone Project’s whole-farmlet experiment on the Northern Tablelands of New South Wales, Australia, the fat scores and reproductive performance of ewes were measured to assess the effect of different management systems on these important production parameters over time. The three farmlets (each of 53 ha) included one (farmlet B) subjected to ‘typical’ district management consisting of moderate levels of inputs and a target stocking rate of 7.5 dse/ha, with flexible grazing management across eight paddocks. A second farmlet (A) was managed in a similar fashion to farmlet B with respect to number of paddocks and grazing management, but modified by high rates of pasture renovation and higher levels of soil fertility, with a target stocking rate of 15 dse/ha. The third farmlet (C) was managed at the same level of moderate inputs as farmlet B but employed intensive rotational grazing over 37 paddocks and also had a high target stocking rate of 15 dse/ha. The experiment was conducted over 6.5 years from July 2000 to December 2006. In spite of the fact that target levels of stocking rate were chosen at the beginning of the experiment, stocking rate, together with fat scores and reproduction were treated as emergent properties of each farmlet system. Joining took place in April–May and lambing occurred in September–October of each year. Over the first 2 years of the experiment, there were few differences among farmlets in ewe fat scores or reproductive performance. From 2003 onwards, while the percentage of ewes pregnant was similar between farmlets, the average proportion of multiple births (ewes scanned in late July, with twins) was 30%, 16% and 12%, respectively, on farmlets A–C. However, lamb losses were greater on farmlet A, with average lamb mortalities recorded on farmlets A–C of 29%, 10% and 19%, respectively. Over the duration of the experiment, ewes on farmlets A and B were more often above a fat score level of 3, and less often below 2.5, than were ewes from farmlet C. Differences among farmlet ewes in fat score were found to be significant in 7 of the total of 13 assessments over the duration of the experiment. A generalised additive model applied to whole-farmlet data showed that green digestible herbage, legume herbage, stocking rate, the amount of supplement fed and especially the proportion of each farmlet grazed at any one time all influenced fat scores of ewes. While fat scores and conception rates tended to be highest on farmlet A, farmlet B had slightly better reproductive outcomes due to less lambing losses, whereas ewes on farmlet C tended to have somewhat lower fat scores and levels of reproduction. These farmlet-scale findings highlighted the importance for livestock managers to focus not only on grazing management, stocking rate and stock density during lambing, but also on the availability of sufficient green, and especially legume herbage, and the difficulty of overcoming a deficit in quality herbage with supplementation.

Changes in botanical composition on three farmlets subjected to different pasture and grazing management strategies

As part of the Cicerone Project’s farmlet experiment, conducted on the Northern Tablelands of New South Wales, Australia, between July 2000 and December 2006, this study assessed the effects of varying soil fertility, pasture species and grazing management on the botanical composition of three 53-ha farmlets subjected to different management strategies. Starting with the same initial conditions, the farmlets were managed to reach different target levels of soil phosphorus (P) and sulfur (S); Farmlet A aimed at 60 mg/kg of Colwell P and 10 mg/kg S (KCl40) whereas Farmlets B and C both aimed at 20 and 6.5 mg/kg of P and S, respectively. Pastures were renovated on six out of eight paddocks on Farmlet A, but only one paddock of each of Farmlets B (typical management) and C (intensive rotational grazing) was renovated. Flexible rotational grazing was employed on Farmlets A and B (each of eight paddocks) while Farmlet C used intensive rotational grazing over its 17 major paddocks, which were further subdivided into 37 subpaddocks. This paper focuses on the botanical composition dynamics observed across all three farmlets and the explanatory variables associated with those changes. Eight assessments of botanical composition were carried out at approximately annual intervals across each of the 37 major paddocks distributed across the farmlets and the results for each of 49 species were aggregated into seven functional groups for analysis. The strongest correlation found was a negative curvilinear relationship between sown perennial grasses (SPG) and warm-season grasses (WSG). The most significant factors affecting the functional group changes were soil P, sowing phase, paddock and date. These factors led to significant increases in SPG and correspondingly lower levels of WSG on Farmlet A compared with Farmlet B. Farmlets B and C experienced similar, declining levels of SPG, and increasing levels of WSG suggesting that intensive rotational grazing did not lead to substantial changes in botanical composition, compared with flexible rotational grazing, in spite of the fact that intensive rotational grazing had much longer grazing rests and shorter graze periods than the other two farmlets. Soil P levels were also significantly associated with levels of cool-season annual grasses, legumes and herbs, especially on Farmlet A. In general, the largest differences in botanical composition were between Farmlet A and the other two farmlets; these differences were most closely associated with those plants categorised as sown, introduced, C3 pasture species. The levels of legume were generally low on all farmlets, due largely to the dry seasons experienced over most of the trial. Efforts to increase the legume composition on all farmlets were more successful on Farmlet A than on the other two farmlets due, presumably, to higher soil fertility on Farmlet A. Farmlet C, with its long rest periods and short graze periods, had a small proportion of legumes, due to the competitive effects of the accumulated tall grass herbage between grazings. The ‘typical’ management of Farmlet B also resulted in low levels of legume as well as increased ‘patchiness’ of the pastures and increased numbers of thistles.

Estimating the balance between pasture feed supply and demand of grazing livestock in a farmlet experiment

Data from the Cicerone farmlet study were used to quantify the balance between pasture feed supply and the demand from grazing livestock, in terms of metabolisable energy (ME), on three differently managed farmlets (each of 53 ha) on the Northern Tablelands of New South Wales, Australia. Farmlet A had a high level of pasture renovation and higher soil fertility than the other two farmlets and employed flexible grazing management over eight paddocks. Farmlet B was designed to represent management ‘typical’ of the region and had the same grazing management and number of paddocks as farmlet A but moderate levels of pasture renovation and soil fertility. The third farmlet (C) had the same level of inputs as farmlet B but practised intensive rotational grazing over 37 paddocks. Regular measurements of the feed supply, namely herbage mass and quality, pasture growth and supplement fed and of feed demand were assembled to provide monthly estimates of the balance between feed supply and animal demand of all classes of livestock run on the experiment over its duration of 6.5 years. The significantly greater stocking rate, liveweight and reproductive rate of sheep reached on the higher input system (farmlet A) meant higher levels of ME were required to satisfy the nutritional demands of these animals. As only limited measurements were taken of animal intake, it was assumed that the supply of ME was derived from pasture growth and supplement fed. Using key livestock management dates and measurements of liveweights, the changes in the energy requirements of each class of animal were calculated and aggregated to provide an estimate of overall livestock energy demand over time. Subtracting the energy demand from the estimated energy supply provided a partial net energy balance. Measurements of the rates of change of green herbage during grazing events were found to be highly dependent on stock density with farmlets A, B and C recording rates of change of up to –50, –30 and –200 green DM/ha.day, respectively. Over a series of generally drier-than-average years, the ME supplied in pasture growth and through supplementation was at times inadequate to meet the energy demands of the livestock, resulting in periods during winter when the partial energy balance became negative. Similar feed deficits were observed for all three farmlets, suggesting that they were over-stocked to a similar extent. In spite of the divergence in the stocking rate supported by each farmlet, the similarity of the ME balances between farmlets suggests that no farmlet was subjected to bias because of decisions relating to feed supply and demand. The analyses presented suggest there is considerable potential for practical paddock and grazing management to be improved if more timely and regular assessments can be made of changes in the feed energy supply using satellite images of normalised difference vegetation indices and feed energy demand using calculations of the ME required by grazing livestock.

Pasture herbage mass, quality and growth in response to three whole-farmlet management systems

The effects of different whole-farm management systems were explored in a farmlet trial on the Northern Tablelands of New South Wales, Australia, between July 2000 and December 2006. The three systems examined were first, a moderate input farmlet with flexible grazing on eight paddocks considered ‘typical’ of the region (farmlet B), a second, also with flexible grazing on eight paddocks but with a high level of pasture renovation and increased soil fertility (farmlet A) and a third with the same moderate level of inputs as farmlet B but which practised intensive rotational grazing on 37 paddocks (farmlet C). The changes in herbage mass, herbage quality and pasture growth followed a seasonal pattern typical of the Northern Tablelands with generally higher levels recorded over spring–summer and lower levels in autumn–winter but with substantial differences between years due to the variable climate experienced. Over the first 18 months of the trial there were no significant differences between farmlets in total herbage mass. Although the climate was generally drier than average, the differences between farmlets in pasture herbage mass and quality became more evident over the duration of the experiment. After the farmlet treatments started to take effect, the levels of total and dead herbage mass became significantly lower on farmlet A compared with farmlets B and C. In contrast, the levels of green herbage were similar for all farmlets. Throughout most of the study period, pastures on farmlet A with its higher levels of pasture renovation and soil fertility, had significantly higher DM digestibility for both green and dead herbage components compared with pastures on either of the moderate input systems (B and C). Thus, when green herbage mass and quality were combined, farmlet A tended to have higher levels of green digestible herbage than either of the other farmlets, which had similar levels, suggesting that pasture renovation and soil fertility had more effect on the supply of quality pasture than did grazing management. This difference was observed in spite of the higher stocking rate supported by farmlet A after treatments took effect. Levels of legume herbage mass, while generally low due to the dry conditions, were significantly higher on farmlet A compared with the other two farmlets. While ground cover on farmlet A was found to be less than the other farmlets, this was largely associated with the higher level of pasture renovation. Generally, all three farmlets had ground cover levels well above 70% for the duration of the experiment, thus being above levels considered critical for prevention of erosion. A multivariate analysis showed that the main explanatory factors significantly linked (P < 0.01) with the supply of high quality herbage were, in decreasing order of importance, those related to season and weather, pasture renovation, grazing management and soil fertility. Measurements of net pasture growth conducted using a limited number of grazing exclosure cages on three paddocks per farmlet revealed clear seasonal trends but no significant (P > 0.05) differences between farmlets. However, post hoc estimates of potential pasture growth rate using remotely sensed MODIS satellite images of normalised difference vegetation index captured weekly from each farmlet revealed a significant (P < 0.001) relationship with the seasonal pattern observed in the measurements of pasture growth rate.

Integrated overview of results from a farmlet experiment which compared the effects of pasture inputs and grazing management on profitability and sustainability

The Cicerone Project conducted a grazed farmlet experiment on the Northern Tablelands of New South Wales, Australia, from July 2000 to December 2006, to address questions raised by local graziers concerning how they might improve the profitability and sustainability of their grazing enterprises. This unreplicated experiment examined three management systems at a whole-farmlet scale. The control farmlet (farmlet B) represented typical management for the region, with flexible rotational grazing and moderate inputs. A second farmlet (farmlet A) also used flexible rotational grazing but had a higher level of pasture renovation and soil fertility, while the third farmlet (farmlet C) had the same moderate inputs as farmlet B but employed intensive rotational grazing. The present paper provides an integrated overview of the results collated from component papers and discusses the inferences that can be drawn from what was a complex, agroecosystem experiment. The measurements recorded both early and late in the experiment were tabulated for each of the farmlets and compared with each other as relative proportions, allowing visual presentation on a common, indexed scale. Because of equivalent starting conditions, there was little difference between farmlets early in the experimental period (2000–01) across a wide array of measured parameters, including herbage mass, potential pasture growth rate, liveweight, wool production per head, stocking rate, gross margin and equity. Although the experiment experienced drier-than-average conditions, marked differences emerged among farmlets over time, due to the effects of treatments. During the latter half of the experimental period (2003–06), farmlet A showed numerous positive and a few negative consequences of the higher rate of pasture renovation and increased soil fertility compared with the other two farmlets. While intensive rotational grazing resulted in superior control of gastrointestinal nematodes and slightly finer wool, this system had few effects on pastures and no positive effects on sheep liveweights, wool production or stocking rate. Whereas farmlet A showed higher gross margins, it had a negative and lower short-term cash position than did farmlets B and C, due largely to the artificially high rate of pasture renovation undertaken on this farmlet during the experiment. Although farmlet B had the highest cash position at the end of the experiment, this came at a cost of the declining quality of its pastures. Modelling of the farmlet systems allowed the results to be considered over the longer timeframes needed to assess sustainability. Thus, returns on investment were compared over realistic amortisation periods and produced outcomes based on long-term climatic expectations which were compared with those that arose under the drier-than-average conditions experienced during the experimental period. The main factors responsible for lifting the productivity of farmlet A were the sowing of temperate species and increased soil fertility, which enhanced the amount of legume and increased pasture quality and potential pasture growth. The factor that affected farmlet C most was the low proportion of the farmlet grazed at any one time, with high stock density imposed during grazing, which decreased feed intake quality. The paper concludes that more profitable and sustainable outcomes are most likely to arise from grazing enterprises that are proactively managed towards optimal outcomes by maintaining sufficient desirable perennial grasses with adequate legume content, enhancing soil fertility and employing flexible rotational grazing.

Comparing the climate experienced during the Cicerone farmlet experiment against the climatic record

Farming systems research conducted under dryland conditions is subject to the vagaries of the climate during the experimental period. Whether such an experiment experiences a representative series of climatic years must be examined in relation to the longer term climatic record. The Cicerone Project’s farmlet experiment was conducted on the Northern Tablelands of New South Wales, Australia, to investigate the profitability and sustainability of three different management systems: one managed under typical, moderate-input conditions (farmlet B); a second which employed a higher level of pasture inputs and soil fertility (farmlet A); and a third which focussed on the use of moderate inputs and intensive rotational grazing (farmlet C). The climate experienced during the 6.5-year experimental period was compared with the 118-year climatic record, using a biophysical simulation model of grazed systems. The model utilised the long-term daily climate data as inputs and provided outputs that allowed comparison of parameters known to affect grazed pastures. Modelled soil-available water, the number of soil moisture stress days (SMSDs) limiting pasture growth, and growth indices over the experimental period (2000–06) were compared with data over the climatic record from 1890 to 2007. SMSDs were defined as when the modelled available soil moisture to a depth of 300 mm was <17% of water-holding capacity. In addition, minimum temperatures and, in particular, the frequency of frosts, were compared with medium-term (1981–2011) temperature records. Wavelet transforms of rainfall and modelled available soil water data were used to separate profile features of these parameters from the noise components of the data. Over the experimental period, both rainfall and available soil water were more commonly significantly below than above the 95% confidence intervals of both parameters. In addition, there was an increased frequency of severe frosting during the dry winters experienced over the 6.5-year period. These dry and cold conditions were likely to have limited the responses to the pasture and grazing management treatments imposed on the three farmlets. In particular, lower than average levels of available soil water were likely to have constrained pasture production, threatened pasture persistence, and reduced the response of the pasture to available soil nutrients and, as a consequence, livestock production and economic outcomes. Ideally, dryland field experimentation should be conducted over a representative range of climatic conditions, including soil moisture conditions both drier and wetter than average. The drier than average conditions, combined with a higher than normal frequency of severe frosts, mean that the results from the Cicerone Project’s farmlet experiment need to be viewed in the context of the climate experienced over this 6.5-year period.

Grazing systems and worm control in sheep: a long-term case study involving three management systems with analysis of factors influencing faecal worm egg count

Managing infections of sheep with gastrointestinal nematode parasites (worms) and problems of resistance to anthelmintic treatments continue to be major challenges for graziers on the Northern Tablelands of New South Wales, Australia. The whole-farmlet study of grazing enterprises undertaken by the Cicerone Project tested the broad hypotheses that compared with typical management (farmlet B), internal parasites can be more effectively managed with improved nutrition (farmlet A) or by intensive rotational grazing (farmlet C). Further aims were to identify the major sources of variation in faecal worm egg count (WEC) over the 6-year period and to examine the efficacy of the various anthelmintic treatments used during the experiment. This paper describes the management of sheep worms at the whole-farmlet level during the experiment, and analyses data from the routine WEC monitoring (5644 records) and larval differentiation tests (322 records) carried out on behalf of the Cicerone Management Board and by a doctoral candidate. It complements more detailed investigations published elsewhere. Over the period from July 2000 to December 2006, worm infections in ewes, lambs, hoggets and wethers were, with some exceptions, successfully controlled on the farmlets through a combination of regular monitoring of WEC, treatment with a wide array of anthelmintics and grazing management. Farmlet C had lower mean WEC (444 epg) and annual anthelmintic treatment frequency (3.1 treatments/year) over the whole experimental period than farmlets B (1122 epg, 4.3 treatments/year) or A (1374 epg, 4.7 treatments/year). The main factors influencing WEC were the time since the last anthelmintic treatment, and the anthelmintic used at that treatment. The magnitude of these effects dwarfed those of climatic and management factors that might be expected to influence the epidemiology of gastrointestinal nematode infections via environmental or host-mediated mechanisms. Nevertheless management factors associated with stocking rate and grazed proportion (proportion of each farmlet grazed at any one time), and climatic indicators of both temperature and moisture availability had significant effects on WEC. The results show that, in a region with Haemonchus contortus as the major sheep nematode, improved host nutrition in a higher input system (farmlet A) did not provide more effective control of gastrointestinal nematodes than typical management (farmlet B); however, it was observed that gastrointestinal nematode control was no worse on farmlet A than on farmlet B in spite of farmlet A supporting a 48% higher stocking rate by later in the trial period (2005). The study provided strong support for the proposition that intensive rotational grazing (farmlet C) provides more effective control of gastrointestinal nematodes than typical management (farmlet B) as evidenced by significantly lower WEC counts and anthelmintic treatment frequency. Tactical worm control based on routine monitoring of WEC provided adequate control of worms on all three farmlets for much of the experimental period but failed to prevent significant spikes in WEC to values associated with significant production loss on multiple occasions, and significant ewe mortality on farmlets A and B on one occasion.

Obstetric factors and different causes of special educational need: retrospective cohort study of 407,503 schoolchildren

OBJECTIVE

To determine whether relationships with gestational age and birthweight centile vary between specific causes of special educational need (SEN).

DESIGN

Retrospective cohort study.

SETTING

Scotland.

POPULATION

A cohort of 407,503 schoolchildren.

METHODS

Polytomous logistic regression was used to examine the risk of each cause of SEN across the spectrum of gestation at delivery and birthweight centile, adjusting for potential confounding factors.

MAIN OUTCOME MEASURES

Crude and adjusted odds ratios and confidence intervals.

RESULTS

Of the 19,821 children with SEN, 557 (2.8%) had sensory impairments, 812 (4.1%) had physical or motor disabilities, 876 (4.4%) had language impairments, 2823 (14.2%) had social, emotional, or behavioural problems, 7018 (35.4%) had intellectual disabilities, 4404 (22.2%) had specific learning difficulties, and 1684 (8.5%) autistic spectrum disorder (ASD). Extreme preterm delivery (at 24-27 weeks of gestation) was a strong predictor of sensory (adjusted OR 23.64, 95% CI 12.03-46.45), physical or motor (adjusted OR 29.69, 95% CI 17.49-50.40), and intellectual (adjusted OR 11.67, 95% CI 8.46-16.10) impairments, with dose relationships across the range of gestation. Similarly, birthweight below the third centile was associated with sensory (adjusted OR 2.85, 95% CI 2.04-3.99), physical or motor (adjusted OR 2.47, 95% CI 1.82-3.37), and intellectual (adjusted OR 2.67, 95% CI 2.41-2.96) impairments. Together, gestation and birthweight centile accounted for 24.0% of SEN arising from sensory impairment, 34.3% arising from physical or motor disabilities, and 26.6% arising from intellectual disabilities. Obstetric factors were less strongly associated with specific learning difficulties and social or emotional problems, and there were no significant associations with ASD.

CONCLUSIONS

The association between gestation and birthweight centile and overall risk of SEN is largely driven by very strong associations with sensory, physical or motor impairments, and intellectual impairments.