Testing for a genetic response to sexual selection in a wild Drosophila population.

In accordance with the consensus that sexual selection is responsible for the rapid evolution of display traits on macroevolutionary scales, microevolutionary studies suggest sexual selection is a widespread and often strong form of directional selection in nature. However, empirical evidence for the contemporary evolution of sexually selected traits via sexual rather than natural selection remains weak. In this study, we used a novel application of quantitative genetic breeding designs to test for a genetic response to sexual selection on eight chemical display traits from a field population of the fly, Drosophila serrata. Using our quantitative genetic approach, we were able to detect a genetically based difference in means between groups of males descended from fathers who had either successfully sired offspring or were randomly collected from the same wild population for one of these display traits, the diene (Z,Z)-5,9-C27 : 2 . Our experimental results, in combination with previous laboratory studies on this system, suggest that both natural and sexual selection may be influencing the evolutionary trajectories of these traits in nature, limiting the capacity for a contemporary evolutionary response.

Testing the correlated response hypothesis for the evolution and maintenance of male mating preferences in Drosophila serrata.

Mate preferences are abundant throughout the animal kingdom with female preferences receiving the most empirical and theoretical attention. Although recent work has acknowledged the existence of male mate preferences, whether they have evolved and are maintained as a direct result of selection on males or indirectly as a genetically correlated response to selection for female choice remains an open question. Using the native Australian species Drosophila serrata in which mutual mate choice occurs for a suite of contact pheromones (cuticular hydrocarbons or CHCs), we empirically test key predictions of the correlated response hypothesis. First, within the context of a quantitative genetic breeding design, we estimated the degree to which the trait values favoured by male and female choice are similar both phenotypically and genetically. The direction of sexual selection on male and female CHCs differed statistically, and the trait combinations that maximized male and female mating success were not genetically correlated, suggesting that male and female preferences target genetically different signals. Second, despite detecting significant genetic variance in female preferences, we found no evidence for genetic variance in male preferences and, as a consequence, no detectable correlation between male and female mating preferences. Combined, these findings are inconsistent with the idea that male mate choice in D. serrata is simply a correlated response to female choice. Our results suggest that male and female preferences are genetically distinct traits in this species and may therefore have arisen via different evolutionary processes.

Mental imagery in chronic pain: prevalence and characteristics.

BACKGROUND: Research into mental imagery has increased our understanding of a range of psychological problems. However, there has been little study into the spontaneous mental images experienced in response to chronic pain. This study aimed to explore the prevalence and characteristics of these pain-related mental images. METHODS: Four hundred ninety-one people with chronic pain who had attended a pain clinic were sent invites to participate and 105 people responded (21%). A mixed-methods approach (quantitative and qualitative) was used to explore the prevalence of pain-related mental imagery, differences between imagers and non-imagers, and the content of imagery in pain. RESULTS: In our sample, 36% of respondents reported having mental images of their pain, with the majority describing them as clear and vivid (83%), experienced daily (80.5%), and distressing (83%). Participants who experienced mental images reported higher depression scores, higher anxiety and higher pain unpleasantness. Frequency of imagery was associated with greater pain unpleasantness. Content analysis of the pain images revealed emerging themes relating to the sensory qualities of pain, anatomical representations, pain as a form of threat or attack, pain as an object, and pain as an abstract image. CONCLUSIONS: This study describes themes and characteristics of pain-related mental imagery and confirms that they are a frequent, vivid and distressing experience for many chronic pain sufferers. The results of this study suggest that pain-related mental imagery could provide an additional route for assessment and intervention. Further research should focus on assessment, measurement and intervention in clinical populations.

On the evolution of heightened condition dependence of male sexual displays.

The maintenance of genetic variation in male sexual display traits in the face of strong directional sexual selection from female preferences is an ongoing evolutionary conundrum. Condition dependence and the genic capture hypothesis are often cited as theoretical resolutions to this problem, yet little is known about the ability of condition dependence itself to evolve. We set out to test how a suite of cuticular hydrocarbons (CHCs) used in sexual displays are affected by adult diet and the potential for any condition-dependent response to evolve in a laboratory-adapted population of the Australian fruit fly Drosophila serrata. We performed a dietary manipulation within a half-sib breeding design, raising adult males either with or without access to live yeast, a manipulation that had previously shown strong effects on female fitness. Diet had strong phenotypic effects, with males from the different diets producing different CHC blends. The blend of CHCs under sexual selection showed a degree of elevated condition dependence. Regardless of the heightened sensitivity of favoured CHC blends to diet and the presence of genetic variance for the traits, we were unable to detect any genetic variance in the reaction norms for the male dietary response. Our results suggest that there is limited opportunity for males to evolve further condition dependence in response to yeast availability in this population.

Patterns of differentiation in a colour polymorphism and in neutral markers reveal rapid genetic changes in natural damselfly populations.

The existence and mode of selection operating on heritable adaptive traits can be inferred by comparing population differentiation in neutral genetic variation between populations (often using F(ST) values) with the corresponding estimates for adaptive traits. Such comparisons indicate if selection acts in a diversifying way between populations, in which case differentiation in selected traits is expected to exceed differentiation in neutral markers [F(ST )(selected) > F(ST )(neutral)], or if negative frequency-dependent selection maintains genetic polymorphisms and pulls populations towards a common stable equilibrium [F(ST) (selected) < F(ST) (neutral)]. Here, we compared F(ST) values for putatively neutral data (obtained using amplified fragment length polymorphism) with estimates of differentiation in morph frequencies in the colour-polymorphic damselfly Ischnura elegans. We found that in the first year (2000), population differentiation in morph frequencies was significantly greater than differentiation in neutral loci, while in 2002 (only 2 years and 2 generations later), population differentiation in morph frequencies had decreased to a level significantly lower than differentiation in neutral loci. Genetic drift as an explanation for population differentiation in morph frequencies could thus be rejected in both years. These results indicate that the type and/or strength of selection on morph frequencies in this system can change substantially between years. We suggest that an approach to a common equilibrium morph frequency across all populations, driven by negative frequency-dependent selection, is the cause of these temporal changes. We conclude that inferences about selection obtained by comparing F(ST) values from neutral and adaptive genetic variation are most useful when spatial and temporal data are available from several populations and time points and when such information is combined with other ecological sources of data.

Solving inequities in provider distribution: loan repayment.

The distribution of primary health care professionals in England and Wales is inequitable, with relatively lower concentrations of professionals in deprived areas. The objective of the present study was to determine whether graduate health professionals would be willing to work in under-served areas in return for educational loan repayment. The study group consisted of a convenience sample of 50 newly qualified and trainee general practitioners, and 50 newly qualified community nurses and health visitors in mid- and west Wales. At interview, the subjects were presented with descriptions of general practices and asked to indicate their preferred practice. Practice descriptions varied systematically in terms of location (i.e. urban, suburban and rural), population deprivation (i.e. deprived or mixed affluent/deprived) and availability of loan repayment (i.e. none or loans paid off over a period of between one and 4 years). The main outcome was the probability that a practice with loan repayment was chosen. Compared with a suburban practice, a one-year loan repayment option made the rural and urban deprived practices 1.6 times and 1.2 times more likely to be chosen, respectively. Nurses were generally more willing than doctors to work in a deprived area in return for loan repayment. The findings suggest that loan repayment may offset health professionals' aversion to working in deprived areas. Such a scheme needs to be piloted to see whether it does offer value for money in recruiting health professionals to under-served areas.

Are specialist outreach clinics for orthodontic consultation effective? A randomised controlled trial.

OBJECTIVE: To develop outreach clinics for orthodontic consultation and evaluate their costs and effectiveness. DESIGN: Single centre randomised controlled trial with random allocation of referred patients to outreach or main base consultation appointments. SETTING: One hospital orthodontic department and three community health centre clinics in Greater Manchester. Subjects 324 patients who were referred for orthodontic treatment. MAIN OUTCOME MEASURES: The outcome of consultation, the cost and duration of the visit and the consumer's perceptions of the visit. RESULTS: There were no differences in outcome of the consultation. While consumer travel costs and the duration of appointments were significantly higher for the main base clinics, these differences were not great. However, consumers preferred to attend an appointment in an outreach clinic. CONCLUSIONS: There do not appear to be marked advantages or disadvantages in providing consultation appointments for orthodontics in outreach clinics

A profile of PMS salaried GP contracts and their impact on recruitment.

BACKGROUND: Personal medical services (PMS) pilot sites aim to use salaried GP schemes to improve GP recruitment and retention and enhance the quality of service provision, particularly in underserved areas. OBJECTIVES: Our objectives were to (i) compare the work incentives of salaried compared with standard GP contracts; (ii) assess recruitment success to salaried posts; and (iii) describe the types of GPs attracted to these new posts. METHOD: All first wave PMS pilot sites with salaried GP posts known to be 'live' in October 1998 were included in the analysis of employment contracts and job descriptions. Information on recruitment was obtained by a questionnaire survey of PMS sites that were intending to recruit a salaried GP. RESULTS: The mean full-time equivalent salary was 43,674 pounds sterling with additional benefits in terms of sick leave, maternity leave and paid expenses. Eighty-nine percent of posts were eligible for the NHS pension scheme. Posts were mainly full time (40.8 hours per week). GPs were responsible for providing services equivalent in scope to general medical services. One-fifth of contracts freed GPs from out-of-hours responsibility and most freed them from practice management. Forty-three of the pilot sites actively recruited to fill 63 salaried posts, which involved a total of 51 recruitment 'rounds', with some pilots advertising more than once. There were 291 applications. The median number of applicants per post was three and the median time to recruitment was 6 weeks. Eighty-five percent of sites were satisfied with the quality of their applicants and 64% with the quantity. Eighty-five percent of applicants previously had been working in general practice, most in locum or salaried posts. Applicants tended to be young and male. Sixty posts were filled. CONCLUSIONS: Salaried contracts offer positive incentives to recruitment in terms of reduced hours of work and freedom from administrative responsibility. Recruitment success was similar to that achieved by inner city practices generally. This modest achievement might be enhanced by the addition of professional development schemes and increased flexible/part-time working.

Impact of payment method on behaviour of primary care physicians: a systematic review.

OBJECTIVE: To review the impact of payment systems on the behaviour of primary care physicians. METHODS: All randomised trials, controlled before and after studies, and interrupted time series studies that compared capitation, salary, fee-for-service or target payments (mixed or separately) that were identified by computerised searches of the literature. Methodological quality assessment and data extraction were undertaken independently by two reviewers using a data checklist. Study results were qualitatively analysed. RESULTS: Six studies met the inclusion criteria. There was considerable variation in the quality of reporting, study setting and the range of outcomes measured. Fee-for-service resulted in a higher quantity of primary care services provided compared with capitation but the evidence of the impact on the quantity of secondary care services was mixed. Fee-for-service resulted in more patient visits, greater continuity of care, higher compliance with a recommended number of visits, but lower patient satisfaction with access to a physician compared with salary payment. The evidence of the impact of target payment on immunisation rates was inconclusive. CONCLUSIONS: There is some evidence to suggest that how a primary care physician is paid does affect his/her behaviour but the generalisability of these studies is unknown. Most policy changes in the area of payment systems are inadequately informed by research. Future changes to doctor payment systems need to be rigorously evaluated.

Target payments in primary care: effects on professional practice and health care outcomes.

BACKGROUND: The method by which physicians are paid may affect their professional practice. Although payment systems may be used to achieve policy objectives (e.g. improving quality of care, cost containment and recruitment to under-served areas), little is known about the effects of different payment systems in achieving these objectives. Target payments are a payment system which remunerate professionals only if they provide a minimum level of care. OBJECTIVES: To evaluate the impact of target payments on the professional practice of primary care physicians (PCPs) and health care outcomes. SEARCH STRATEGY: We searched the Cochrane Effective Practice and Organisation of Care Group specialised register; the Cochrane Controlled Trials Register; MEDLINE (1966 to October 1997); BIDS EMBASE (1980 to October 1997); BIDS ISI (1981 to October 1997); EconLit (1969 to October 1997); HealthStar (1975 to October 1997) Helmis (1984 to October 1997); health economics discussion paper series of the Universities of York, Aberdeen, Sheffield, Bristol, Brunel, and McMaster; Swedish Institute of Health Economics; RAND corporation; and reference lists of articles. SELECTION CRITERIA: Randomised trials, controlled before and after studies and interrupted time series analyses of interventions comparing the impact of target payments to primary care professionals with alternative methods of payment, on patient outcomes, health services utilisation, health care costs, equity of care, and PCP satisfaction with working environment. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data and assessed study quality. MAIN RESULTS: Two studies were included involving 149 practices. The use of target payments in the remuneration of PCPs was associated with improvements in immunisation rates, but the increase was statistically significant in only one of the two studies. REVIEWER'S CONCLUSIONS: The evidence from the studies identified in this review is not of sufficient quality or power to obtain a clear answer to the question as to whether target payment remuneration provides a method of improving primary health care. Additional efforts should be directed in evaluating changes in physicians' remuneration systems. Although it would not be difficult to design a randomised controlled trial to evaluate the impact of such payment systems, it would be difficult politically to conduct such trials.

Capitation, salary, fee-for-service and mixed systems of payment: effects on the behaviour of primary care physicians.

BACKGROUND: It is widely believed that the method of payment of physicians may affect their clinical behaviour. Although payment systems may be used to achieve policy objectives (e.g. cost containment or improved quality of care), little is known about the effects of different payment systems in achieving these objectives. OBJECTIVES: To evaluate the impact of different methods of payment (capitation, salary, fee for service and mixed systems of payment) on the clinical behaviour of primary care physicians (PCPs). SEARCH STRATEGY: We searched the Cochrane Effective Practice and Organisation of Care Group specialised register; the Cochrane Controlled Trials Register; MEDLINE (1966 to October 1997); BIDS EMBASE (1980 to October 1997); BIDS ISI (1981 to October 1997); EconLit (1969 to October 1997); HealthStar (1975 to October 1997) Helmis (1984 to October 1997); health economics discussion paper series of the Universities of York, Aberdeen, Sheffield, Bristol, Brunel, and McMaster; Swedish Institute of Health Economics; RAND corporation; and reference lists of articles. SELECTION CRITERIA: Randomised trials, controlled before and after studies and interrupted time series analyses of interventions comparing the impact of capitation, salary, fee for service (FFS) and mixed systems of payment on primary care physician satisfaction with working environment; cost and quantity of care; type and pattern of care; equity of care; and patient health status and satisfaction. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data and assessed study quality. MAIN RESULTS: Four studies were included involving 640 primary care physicians and more than 6400 patients. There was considerable variation in study setting and the range of outcomes measured. FFS resulted in more primary care visits/contacts, visits to specialists and diagnostic and curative services but fewer hospital referrals and repeat prescriptions compared with capitation. Compliance with a recommended number of visits was higher under FFS compared with capitation payment. FFS resulted in more patient visits, greater continuity of care, higher compliance with a recommended number of visits, but patients were less satisfied with access to their physician compared with salaried payment. REVIEWER'S CONCLUSIONS: It is noteworthy that so few studies met the inclusion criteria. There is some evidence to suggest that the method of payment of primary care physicians affects their behaviour, but the findings' generalisability is unknown. More evaluations of the effect of payment systems on PCP behaviour are needed, especially in terms of the relative impact of salary versus capitation payments.

How do general practitioners choose their practice? Preferences for practice and job characteristics.

OBJECTIVES: To investigate the strength of preferences for practice and job characteristics among recently appointed general practitioners (GPs) in south-east England. METHODS: Conjoint analysis based on a postal questionnaire survey of all 293 GPs who joined a new practice between April 1997 and March 1998 in London, Essex and Hertfordshire. GPs were presented with descriptions of practices in pairs, which varied systematically for key characteristics, and asked to indicate their preferred practice in each pair. RESULTS: The response rate was 58.7%. The most important influence on GPs' choice of practice was aversion to location in an area of high deprivation. They were more likely to choose a practice that: had an extended primary health care team; offered opportunities to develop outside interests; and offered them higher income, shorter working hours and smaller list sizes. The model generated estimates of the strength of these preferences. For example, GPs would require additional income of just over 5000 Pounds per annum to work in an area with a high proportion of deprived patients. CONCLUSIONS: Potential policy interventions to attract GPs to under-served areas include increasing their level of remuneration, providing opportunities to develop outside interests and ensuring that practices have a primary health care team.

How should we pay doctors? A systematic review of salary payments and their effect on doctor behaviour.

We reviewed the published and unpublished international literature to determine the influence of salaried payment on doctor behaviour. We systematically searched Medline, BIDS Embase, Econlit and BIDS ISI and the reference lists of located papers to identify relevant empirical studies comparing salaried doctors with those paid by alternative methods. Only studies which reported objective outcomes and measures of the behaviour of doctors paid by salary compared to an alternative method were included in the review. Twenty-three papers were identified as meeting the selection criteria. Only one of the studies in this review reported a proxy for health status, but none examined whether salaried doctors differentiated between patients on the basis of health needs. Therefore, we were unable to draw conclusions on the likely impact of salaried payment on efficiency and equity. However, the limited evidence in our review does suggest that payment by salaries is associated with the lowest use of tests, and referrals compared with FFS and capitation. Salary payment is also associated with lower numbers of procedures per patient, lower throughput of patients per doctor, longer consultations, more preventive care and different patterns of consultation compared with FFS payment.

Who contracts for primary care?

The implications of the 1997 NHS (Primary Care) Act have been largely overlooked in the rush to establish Primary Care Groups. Allowing health authorities to develop local contracts for primary care has far-reaching implications and is an important departure from the national system of negotiation that has characterized general practice to date. This paper describes a content analysis of a sample of Personal Medical Services (PMS) pilot contracts. In the first year little attention has been given to achieving cost savings or greater efficiency and few contracts promote clinical guidelines. The difficulties of specifying services sensitive to local health needs are highlighted and the national Statement of Fees and Allowances (the 'Red Book') may not be swiftly supplanted. However, the pilots have introduced innovations such as salaried general practitioners, nurse-led services and NHS trust-managed care. The development of local contracts provides a valuable learning experience for general practitioners and health authorities in advance of the establishment of Primary Care Trusts.

Specialist outreach clinics in general practice: what do they offer?

BACKGROUND: Specialist outreach clinics in general practice, in which hospital-based specialists hold outpatient clinics in general practitioners' (GPs) surgeries, are one example of a shift in services from secondary to primary care. AIM: To describe specialist outreach clinics held in fundholding general practices in two specialties from the perspective of patients, GPs, and consultants, and to estimate the comparative costs of these outreach clinics and equivalent hospital outpatient clinics. METHOD: Data were collected from single outreach sessions in fundholding practices and single outpatient clinics held by three dermatologists and three orthopaedic surgeons. Patients attending the outreach and outpatient clinics, GPs from practices in which the outreach clinics were held, and the consultants all completed questionnaires. Managers in general practice and hospital finance departments supplied data for the estimation of costs. RESULTS: Initial patient questionnaires were completed by 83 (86%) outreach patients and 81 (75%) outpatients. The specialist outreach clinics sampled provided few opportunities for increased interaction between specialists and GPs. Specialists were concerned about the travelling time resulting from their involvement in outreach clinics. Waiting times for first appointments were shorter in some outreach clinics than in outpatient clinics. However, patients were less concerned about the location of their consultation with the specialist than they were about the interpersonal aspects of the consultation. There was some evidence of a difference in casemix between the dermatology patients seen at outreach and those seen at outpatient clinics, which confounded the comparison of total costs associated with the two types of clinic. However, when treatment and overhead costs were excluded, the marginal cost per patient was greater in outreach clinics than in hospital clinics for both specialties studied. CONCLUSION: The study suggests that a cautious approach should be taken to further development of outreach clinics in the two specialties studied because the benefits of outreach clinics to patients, GPs and consultants may be modest, and their higher cost means that they are unlikely to be cost-effective.

The economics of osteoporosis prevention.

Until recently, it was generally assumed that the prevention of a significant proportion of osteoporotic fractures could only be achieved through the use of hormone replacement therapy soon after menopause. It is likely to be more cost-effective, however, if antifracture therapy could be undertaken among older, higher risk populations. Recent evidence suggests that there are a number of effective interventions that can be used among the over-65 age group, and the economic evidence supports the view that this is likely to be the best way forward for fracture prevention.