The use of the propensity score for estimating treatment effects: administrative versus clinical data

There is an increasing interest in using administrative data to estimate the treatment effects of interventions. While administrative data are relatively inexpensive to obtain and provide population coverage, they are frequently characterized by lack of clinical detail, often leading to problematic confounding when they are used to conduct observational research. Propensity score methods are increasingly being used to address confounding in estimating the effects of interventions in such studies. Using data on patients discharged from hospital for whom both administrative data and detailed clinical data obtained from chart reviews were available, we examined the degree to which stratifying on the quintiles of propensity scores derived from administrative data was able to balance patient characteristics measured in clinical data. We also determined the extent to which measures of treatment effect obtained using propensity score methods were similar to those obtained using traditional regression methods. As a test case, we examined the treatment effects of ASA and beta-blockers following acute myocardial infarction. We demonstrated that propensity scores developed using administrative data do not necessarily balance patient characteristics contained in clinical data. Furthermore, measures of treatment effectiveness were attenuated when obtained using clinical data compared to when administrative data were used.

Readers guide to critical appraisal of cohort studies: 3. Analytical strategies to reduce confounding

Analytical strategies can help deal with potential confounding but readers need to know which strategy is appropriate

Reader's guide to critical appraisal of cohort studies: 2. Assessing potential for confounding

Although confounding is an important problem of cohort studies, its effects can be minimised to enable valid comparison

Reader's guide to critical appraisal of cohort studies: 1. Role and design

Cohort studies can provide valuable information unavailable from randomised trials, but readers need to be alert to possible flaws

Impact of the choice of benchmark on the conclusions of hospital report cards

BACKGROUND

Hospital report cards for outcomes following acute myocardial infarction (AMI) are being produced with increasing frequency. Implicit in the statistical methods used is the fact that hospitals are being compared with an average hospital. Prior research has demonstrated that institutional characteristics such as a high annual volume of AMI patients and academic status are associated with improved outcomes. This raises the important issue of what is an appropriate benchmark against which hospitals should be compared. The objective of the current study was to determine whether the number of hospitals identified as mortality outliers depended upon the benchmark against which hospitals are compared.

METHODS

We examined all patients discharged with a diagnosis of AMI from 163 Ontario hospitals between April 1, 2000, and March 30, 2001. Logistic regression models that incorporated random provider effects were used to identify hospitals with a mortality rate significantly higher than average. The initial model included only patient characteristics, whereas additional models incorporated both patient and hospital characteristics.

RESULTS

After adjusting for patient characteristics only, 3 hospitals had significantly higher mortality compared to an average-mortality hospital, while 4 hospitals had significantly lower mortality than an average-mortality hospital. However, after further adjusting for peer group, only 1 hospital was identified as having significantly lower mortality than an average-mortality institution in its peer group.

CONCLUSIONS

The use of peer-group-defined rather than overall benchmarks has a substantial impact on the identification of mortality outliers. The choice of the appropriate benchmark is related to the underlying purpose of the comparison.

Autism as a disorder of neural information processing: directions for research and targets for therapy

The broad variation in phenotypes and severities within autism spectrum disorders suggests the involvement of multiple predisposing factors, interacting in complex ways with normal developmental courses and gradients. Identification of these factors, and the common developmental path into which they feed, is hampered by the large degrees of convergence from causal factors to altered brain development, and divergence from abnormal brain development into altered cognition and behaviour. Genetic, neurochemical, neuroimaging, and behavioural findings on autism, as well as studies of normal development and of genetic syndromes that share symptoms with autism, offer hypotheses as to the nature of causal factors and their possible effects on the structure and dynamics of neural systems. Such alterations in neural properties may in turn perturb activity-dependent development, giving rise to a complex behavioural syndrome many steps removed from the root causes. Animal models based on genetic, neurochemical, neurophysiological, and behavioural manipulations offer the possibility of exploring these developmental processes in detail, as do human studies addressing endophenotypes beyond the diagnosis itself.

Potentially Inappropriate Prescribing in Ontario Community-Dwelling Older Adults and Nursing Home Residents

OBJECTIVES

To compare patterns of potentially inappropriate drug therapy prescribing in community-dwelling older adults and nursing home residents in Ontario, Canada.

DESIGN

A retrospective cohort study using administrative databases.

SETTING

Ontario community and nursing home facilities.

PARTICIPANTS

All 1,275,619 older adults aged 66 and older in Ontario (1,216,900 community-dwelling and 58,719 nursing home residents) who were dispensed at least one prescription from the comprehensive provincial drug plan in 2001. In Ontario, the provision of clinical pharmacy services is mandated in the nursing home setting. No comparable program exists for older adults in the community setting.

MEASUREMENTS

Potentially inappropriate drug prescribing was compared between community-dwelling and nursing home residents in two categories: those to always avoid and therapies considered rarely appropriate to prescribe.

RESULTS

Of the 1,275,619 adults in the cohort, nursing home residents were older (mean age+/-standard deviation=84.2+/-7.6 vs 75.0+/-6.5, P<.001), included more women (73.3% vs 57.7%, P<.001), had higher comorbidity scores (measured by the number of distinct drug therapies dispensed in the prior year (10.7+/-6.8 vs 7.2+/-5.7, P<.001) and Charlson comorbidity scores (1.4+/-1.6 vs 0.9+/-1.5, P<.001)) than community-dwelling individuals. Community-dwelling older adults were significantly more likely to be dispensed at least one drug therapy in the always avoid or rarely appropriate category than nursing home residents (3.3% vs 2.3%, P<.001). Using a logistic regression model that controlled for age, sex, and comorbidity (number of distinct drug therapies dispensed in the prior year), nursing home residents were close to half as likely to be dispensed one of these potentially inappropriate drug therapies as community-dwelling older adults (odds ratio=0.52, 95% confidence interval=0.49-0.55, P<.001).

CONCLUSION

Potentially inappropriate drug therapy in the always avoid and rarely indicated categories is dispensed less often to nursing home residents than to older community-dwelling adults. Clinical pharmacist services, which are mandated in the nursing home setting, may be responsible for these differences in Ontario, Canada.

Use of angiotensin-converting enzyme inhibitor therapy and dose-related outcomes in older adults with new heart failure in the community

OBJECTIVE

To evaluate the dose-related benefit of angiotensin-converting enzyme (ACE) inhibitor therapy among older adults with heart failure and to evaluate whether low-dose ACE inhibitor therapy is better than none.

DESIGN

Observational cohort study.

SETTING

Community-dwelling older adults in Ontario, Canada.

PATIENTS/PARTICIPANTS

We identified 16539 adults 66 years or older who survived 45 days following their first heart failure hospitalization discharge.

MEASUREMENT AND MAIN RESULTS

Multivariate techniques including propensity scores were used to study the association between the dose of ACE inhibitor therapy dispensed and 3 outcomes: survival, survival or heart failure rehospitalization, and survival or all-cause hospitalization at 1 year of follow-up. Logistic regression models explored the association between initial dose dispensed and subsequent dose reduction or drug cessation. Overall, 10793 (65.3%) of patients were dispensed ACE inhibitor therapy, with more than a third (3935; 36.5%) initiated on low-dose therapy. Relative to dispensing of low-dose ACE inhibitor therapy, nonuse was associated with increased mortality (hazard ratio [HR], 1.12; 95% confidence interval [CI], 1.02 to 1.22). Dispensing medium-dose therapy provided a benefit similar to low-dose (HR, 0.94; CI, 0.86 to 1.03) and dispensing of high-dose therapy was associated with improved survival benefit (HR, 0.76; CI, 0.68 to 0.85). Relative to dispensing of low-dose ACE inhibitor therapy, dispensing high-dose conferred a benefit (HR, 0.87; CI, 0.80 to 0.95) on the composite outcome of 1-year mortality or heart failure hospitalization and the composite outcome of 1-year mortality or all-cause hospitalization (HR, 0.87; CI, 0.81 to 0.93). Relative to those dispensed low-dose ACE inhibitor therapy, those initially dispensed high-dose therapy were twice as likely to have their subsequent dose reduced or the therapy discontinued (odds ratio, 2.36; CI, 2.07 to 2.69).

CONCLUSION

Our findings suggest that when possible, older adults should be titrated to the higher doses of ACE inhibitor therapy evaluated in clinical trials. If older adults cannot tolerate higher doses, then low-dose ACE inhibitor therapy is superior to none. High-dose ACE inhibitor therapy is not as well tolerated as lower doses.

Neuroleptic Drug Therapy in Older Adults Newly Admitted to Nursing Homes: Incidence, Dose, and Specialist Contact

OBJECTIVES

To describe the incidence and dose of neuroleptic drug therapy newly dispensed for behavioral disorders to older adults admitted to nursing homes and to determine whether this use is associated with patient characteristics and contact with specialists.

DESIGN

A retrospective cohort study using administrative data from a comprehensive and universal drug program.

SETTING

All licensed nursing homes in Ontario, Canada.

PARTICIPANTS

All 19,780 adults aged 66 and older who had no evidence of neuroleptic drug use in the previous year and no history of major psychosis and were newly admitted to a nursing home between April 1, 1998, and March 31, 2000.

MEASUREMENTS

Exposure to neuroleptic drug therapy and initial dose were measured using claims submitted to the Ontario Drug Benefit Program.

RESULTS

A prescription for a neuroleptic therapy was dispensed to 17% of older adults with no previous neuroleptic exposure within 100 days and to 24% within 1 year of their nursing home admission. New exposure to a neuroleptic therapy was less likely in women (odds ratio (OR)=0.7, 95% confidence interval (CI)=0.6-0.8) and more likely in residents with dementia (OR=3.5, 95% CI=3.2-3.8). Almost 10% of nursing home residents received an initial dose that exceeded recommended thresholds. Only 14% of those newly exposed had prior contact with a geriatrician or psychiatrist.

CONCLUSION

Incident use of neuroleptics in Ontario nursing homes is substantial. Use of high doses suggests that some physicians may need better information about using these agents, particularly given the rapid adoption of atypical neuroleptic drug therapies.

Serotonin uptake and metabolism by cultured guinea pig airway smooth muscle cells

Serotonin (5-hydroxytryptamine, 5-HT) is synthesized and released in the airways by pulmonary neuroendocrine cells located in the vicinity of airway smooth muscle (ASM). The aim of this study was to determine whether ASM cells contribute to the inactivation of serotonin, and investigate the role of the serotonin transporter (SERT) and monoamine oxidase (MAO) in this process. Cultured guinea pig tracheal smooth muscle cells, maintained in culture medium containing serotonin for 1-4 days, induced a decrease in 5-HT and increase in 5-HIAA in the culture medium. Changes in indole concentrations were prevented by fluvoxamine and iproniazid. Na+-sensitive [3H]-serotonin uptake into cultured ASM cells was time- and concentration-dependent (Km, 561 nM; Vmax, 1.06 pmol/mg protein/min), and inhibited by clomipramine (IC50, 13.7 nM), fluvoxamine (IC50, 0.16 microM) and fluoxetine (IC50, 0.32 microM). Western blot analysis with an anti-SERT antibody revealed a single 115 kDa immunoreactive band in ASM cell lysates. The results of this study suggest that ASM contributes to the uptake and metabolism of serotonin via SERT and MAO, respectively, and may therefore play a role in the inactivation of endogenous serotonin generated within the airway wall.

Neurobiology and neuroimmunology of Tourette's syndrome: an update

Tourette's syndrome is a childhood-onset neuropsychiatric disorder characterized by the presence of both multiple motor and vocal tics. While the pathogenesis at a molecular and cellular level remains unknown, structural and functional neuroimaging studies point to the involvement of the basal ganglia and related cortico-striato-thalamo-cortical circuits as the neuroanatomical site for Tourette's syndrome. Moreover, Tourette's syndrome has a strong genetic component, and considerable progress has been made in understanding the mode of transmission and in identifying potential genomic loci. Summaries of recent findings in these areas will be reviewed, followed by a critical overview of findings both supporting and challenging the proposed autoimmune hypothesis of Tourette's syndrome. We conclude that Tourette's syndrome is a heterogeneous disorder, and that immune factors may indeed be involved in some patients.

Representation of patients with dementia in clinical trials of donepezil

OBJECTIVES

To evaluate the representation of frail older adults in randomized controlled trials (RCTs), and to assess consequences of under representation by analyzing drug discontinuation rates.

METHODS

A cohort of older adults newly dispensed donepezil in Ontario between September 2001 and March 2002 was constructed using administrative data. A systematic review of the literature identified RCTs of donepezil. Patients dispensed donepezil were then compared to clinical trial subjects. Discontinuation rates were examined for patients with and without potential contraindications to this drug.

RESULTS

There were 6,424 older adults in the Ontario cohort with new claims for donepezil. Ten RCTs evaluating the use of donepezil were identified (n = 3,423). Between 51% and 78% of the Ontario cohort would have been ineligible for RCT enrollment. Patients dispensed donepezil were older (80.3 vs. 73.7 years, p < 0.001) and more likely to be in long-term care (14.1 vs. 7.1%, p < 0.001) than RCT subjects. Overall, 27.8% of the Ontario cohort discontinued donepezil within seven months of initial prescription. Discontinuation rates were significantly higher for patients with a history of obstructive lung disease, active cardiovascular disease, or Parkinsonism.

CONCLUSIONS

Fewer than half of the older adults dispensed donepezil in Ontario would have been eligible to participate in the RCTs that established the efficacy of this drug. Discontinuation rates were higher among patient groups not represented in the trials. Clinicians should carefully assess the potential risks and benefits of such drug therapies for older patients with dementia.

Potentially Inappropriate Prescribing in Canada Relative to the US

OBJECTIVE

To explore the prescribing of potentially inappropriate drug therapy in Ontario, Canada where there is a restrictive drug formulary relative to the US where there is no single drug formulary.

METHODS

A retrospective, cohort study using an administrative database (Ontario, Canada) compared with published survey results (US). All 1,088,680 community-dwelling adults >or=66 years of age in Ontario, Canada compared with published survey results from 2455 community-dwelling older adults in the US in 1996. Patterns of potentially inappropriate drug prescribing were compared between countries using a list of 33 potentially inappropriate drug therapies. These therapies were classified by an expert panel into three categories: (i) those to always avoid; (ii) those which are rarely appropriate; and (iii) those with only some indications to prescribe.

RESULTS

Among the 33 potentially inappropriate drug therapies, 15 (45%) prescribed in the US were not available through Ontario's drug formulary. Potentially inappropriate drug therapies available through the Ontario Drug Benefit Plan (ODB) and also in the US were frequently prescribed in both Ontario and the US. Differences in prescribing patterns of individual drug therapies were noted between the two countries. Specifically, in the rarely appropriate category, diazepam, a long half-life benzodiazepine, was much more frequently dispensed in Ontario than in the US (3.18% vs 1.37%). In contrast, dextropropoxyphene, an opioid with a poor adverse event profile was more frequently prescribed in the US than in Ontario (6.21% vs 0.74%).

CONCLUSION

Almost half of the potentially inappropriate drug therapies that are available in the US are unavailable from Ontario's drug formulary. Potentially inappropriate drug therapies that were available through the ODB were frequently prescribed in both countries. Alternative approaches that make information immediately accessible to physicians at the time they make prescribing decisions should be considered to improve prescribing practices.

The reproductive response of rams to thyroidectomy: mediation by impaired inhibin feedback rather than a change in LH pulsatility

A series of experiments was conducted to examine the mechanism by which removal of the thyroid glands in seasonally suppressed rams brings about rapid testicular growth. In the first experiment, thyroidectomy at the nadir of the testicular cycle (late winter) initiated testis growth without any detectable change in the extent of spermatogenesis compared with sham-operated controls. The serum concentration of FSH, but not LH, was also markedly increased by thyroidectomy. In the second experiment, serum FSH concentration was again increased by thyroidectomy in late winter but there was no effect of thyroidectomy on LH concentration, LH pulses (measured in frequent blood samples) or testosterone concentration. Furthermore, there was no evidence of a change in central dopaminergic inhibition of GnRH, as measured by the pulsatile LH response to an i.m. injection of the dopaminergic D(2) agonist bromocriptine or antagonist sulpiride. The rapid increase in FSH concentration occurred despite a markedly increased serum inhibin A concentration in thyroidectomized rams. Therefore, the efficacy of inhibin feedback was examined by testing the FSH-suppressive effect of an inhibin preparation (5 ml charcoal-stripped bovine follicular fluid i.v.) in long-term thyroidectomized and thyroid intact castrated rams. Bovine follicular fluid suppressed FSH concentrations in control rams as expected but in marked contrast, was completely without effect in thyroidectomized animals. In castrated rams, the FSH concentration was only marginally increased by thyroidectomy, indicating that there is a major component of the mediation of the effects of thyroidectomy that is testicular in origin. It was concluded that a reduction in the ability of endogenous inhibin to inhibit FSH release at the pituitary, rather than a hypothalamic mechanism, is the primary cause of the stimulation of testis growth by thyroidectomy.

Cortisol response to a cognitive stress challenge in posttraumatic stress disorder (PTSD) related to childhood abuse

Preclinical studies show that animals with a history of chronic stress exposure have increased hypothalamic-pituitary-adrenal (HPA) axis reactivity following reexposure to stress. Patients with posttraumatic stress disorder (PTSD) have been found to have normal or decreased function of the HPA axis, however no studies have looked at the HPA response to stress in PTSD. The purpose of this study was to assess cortisol responsivity to a stressful cognitive challenge in patients with PTSD related to childhood abuse. Salivary cortisol levels, as well as heart rate and blood pressure, were measured before and after a stressful cognitive challenge in patients with abuse-related PTSD (N=23) and healthy comparison subjects (N=18). PTSD patients had 61% higher group mean cortisol levels in the time period leading up to the cognitive challenge, and 46% higher cortisol levels during the time period of the cognitive challenge, compared to controls. Both PTSD patients and controls had a similar 66-68% increase in cortisol levels from their own baseline with the cognitive challenge. Following the cognitive challenge, cortisol levels fell in both groups and were similar in PTSD and control groups. PTSD patients appeared to have an increased cortisol response in anticipation of a cognitive challenge relative to controls. Although cortisol has been found to be low at baseline, there does not appear to be an impairment in cortisol response to stressors in PTSD.

Effect of selective cyclooxygenase 2 inhibitors and naproxen on short-term risk of acute myocardial infarction in the elderly

BACKGROUND

Recent debate has emerged regarding the cardiovascular safety of selective cyclooxygenase 2 inhibitors and the possible cardioprotective effect of naproxen sodium. We compared the rates of acute myocardial infarction (AMI) among elderly patients dispensed selective cyclooxygenase 2 inhibitors, naproxen, and nonselective nonnaproxen nonsteroidal anti-inflammatory drugs (NSAIDs).

METHODS

We conducted a population-based retrospective cohort study using administrative health care data from Ontario, Canada, from April 1, 1998, to March 31, 2001. We identified NSAID-naive cohorts of subjects aged 66 years and older in whom treatment was initiated with celecoxib (n = 15 271), rofecoxib (n = 12 156), naproxen (n = 5669), and nonnaproxen nonselective NSAIDs (n = 33 868), along with a randomly selected control cohort not exposed to NSAIDs (n = 100 000). Multivariate Cox proportional hazards models were used to compare AMI rates between study drug groups while controlling for potential confounders.

RESULTS

Relative to control subjects, the multivariate model showed no significant differences in AMI risk for new users of celecoxib (adjusted rate ratio [aRR], 0.9; 95% confidence interval [CI], 0.7-1.2), rofecoxib (aRR, 1.0; 95% CI, 0.8-1.4), naproxen (aRR, 1.0; 95% CI, 0.6-1.7), or nonnaproxen nonselective NSAIDs (aRR, 1.2; 95% CI, 0.9-1.4).

CONCLUSIONS

The findings of this observational study suggest no increase in the short-term risk of AMI among users of selective cyclooxygenase 2 inhibitors as commonly used in clinical practice. Furthermore, the findings do not support a short-term reduced risk of AMI with naproxen.

Observational study of upper gastrointestinal haemorrhage in elderly patients given selective cyclo-oxygenase-2 inhibitors or conventional non-steroidal anti-inflammatory drugs

OBJECTIVE

To compare rates of upper gastrointestinal haemorrhage among elderly patients given selective cyclo-oxygenase-2 (COX 2) inhibitors and non-selective non-steroidal anti-inflammatory drugs (NSAIDs).

DESIGN

Observational cohort study.

SETTING

Administrative data from Ontario, Canada, used from 17 April 2000 to 31 March 2001 to identify population based, NSAID-naive cohorts of patients.

PATIENTS

Subjects aged > or =66 years who started taking non-selective NSAIDs (n=5391), diclofenac plus misoprostol (n=5087), rofecoxib (n=14 583), or celecoxib (n=18 908) and a randomly selected control cohort not exposed to NSAIDs (n=100 000).

MAIN OUTCOME MEASURES

Rate ratios of hospital admission for upper gastrointestinal haemorrhage in each drug cohort with adjustment for potential confounders.

RESULTS

Relative to controls, the multivariate model revealed an increased short term risk of upper gastrointestinal haemorrhage for users of non-selective NSAIDs (adjusted rate ratio 4.0 (95% confidence intervals 2.3 to 6.9)), diclofenac plus misoprostol (3.0 (1.7 to 5.6)), and rofecoxib (1.9 (1.3 to 2.8)) but not celecoxib (1.0 (0.7 to 1.6)). Relative to celecoxib, significantly higher risks of upper gastrointestinal haemorrhage were observed for non-selective NSAIDs (4.4 (2.3 to 8.5)), diclofenac plus misoprostol (3.2 (1.6 to 6.5)), and rofecoxib (1.9 (1.2 to 2.8)). Relative to rofecoxib, non-selective NSAID users were at significantly higher risk of upper gastrointestinal haemorrhage (1.9 (1.0 to 3.5)).

CONCLUSIONS

This population based observational study found a lower short term risk of upper gastrointestinal haemorrhage for selective COX-2 inhibitors compared with non-selective NSAIDs.

Inappropriate prescribing before and after nursing home admission

OBJECTIVES

To compare the prevalence of inappropriate prescribing before and after nursing home admission and to determine which patient and physician characteristics are associated with inappropriate prescribing in the nursing home setting.

DESIGN

A pre/post retrospective, cohort study.

SETTING

All licensed nursing homes in Ontario, Canada.

PARTICIPANTS

Nineteen thousand nine hundred eleven individuals aged 66 and older, newly admitted to nursing homes in Ontario between April 1, 1997, and March 31, 1999.

MEASUREMENTS

For each patient in the cohort, a subset of the Beers criteria was used to characterize and compare the prevalence of inappropriate prescribing (as indicated by the prescription of one of 49 inappropriate drugs) before and after nursing home admission. A logistic regression model was used to study the association between inappropriate prescribing and patient and physician characteristics.

RESULTS

The proportion of patients receiving a prescription for at least one inappropriate drug decreased from 25.4% before nursing home admission to 20.8% afterward (P <.001). Most patients who had been prescribed an inappropriate agent before nursing home entry had that agent discontinued after admission. The most commonly prescribed inappropriate drugs after nursing home admission were strongly anticholinergic antidepressants (6.4%) and long-half-life benzodiazepines (5.9%). Patients younger than 85 were more likely to receive inappropriate drug therapy (odds ratio (OR) = 1.25, 95% confidence interval (CI) = 1.15-1.35) than those aged 85 and older. Other significant predictors were having more than one prescriber (OR = 1.40, 95% CI = 1.29-1.51), having a physician aged 50 or older (OR = 1.14, 95% CI = 1.05-1.23), having a male physician (OR = 1.20, 95% CI = 1.05-1.37), having a nonspecialist physician (OR = 1.23, 95% CI = 1.01-1.49), having a nonurban physician (OR = 1.13, 95% CI = 1.03-1.24), and having a physician practicing outside the greater Ontario metropolitan area (OR = 1.31, 95% CI = 1.19-1.51).

CONCLUSIONS

Although a substantial number of nursing home residents receive inappropriate drug therapy, the prevalence of inappropriate prescriptions in our cohort declined after nursing home admission despite an overall increase in drug use. Patient and physician characteristics were associated with inappropriate prescribing. Targeted interventions such as regionally based education programs or drug use restrictions may reduce the prevalence of inappropriate prescribing.

"Trial" prescriptions to reduce drug wastage: results from Canadian programs and a community demonstration project

OBJECTIVE

To determine the acceptability of a program to avoid drug wastage through "trial" prescriptions.

STUDY DESIGN

Cross-sectional survey, followed by a 9-month demonstration project.

METHODS

Consultants to trial prescription programs operated by 2 public- and 3 private-sector drug plans in Canada were surveyed. All of the trial prescription programs were voluntary. The demonstration project involved 215 English-speaking adults who filled a "new" prescription for an angiotensin-converting enzyme inhibitor, beta-blocker, or calcium channel blocker (CCB) in 1 of 16 Peterborough, Ontario pharmacies. Patients received a 7-day supply of medication and a reminder card on which the dispensing pharmacist recorded the mutually agreed date and time the patient would be contacted to assess the results of the "trial." Patients who tolerated the medication received the balance of their original prescription.

RESULTS

Most patients (86%) who were offered trials in the demonstration project accepted them, and most (82%) who accepted them found them helpful. The proportion of patients who received the balance varied by program, ranging from 47.1% to 86.6%. The dollar value of the wastage avoided through trial prescriptions varied by drug class. This was driven largely by differences in the unit cost of the medications, but also to a lesser extent by larger prescriptions for CCBs.

CONCLUSIONS

Trial prescriptions were acceptable to patients and, if focused on specific medications, could reduce the direct cost of drug wastage. More work is needed to define the conditions under which trial prescription programs are feasible for pharmacists and drug plans.

Oestradiol microimplants in the ventromedial preoptic area inhibit secretion of luteinizing hormone via dopamine neurones in anoestrous ewes

Oestradiol exerts a season-specific negative feedback effect on the GnRH/LH neurosecretory system of the Suffolk ewe. This neuroendocrine suppression is mediated in part by dopamine A15 neurones, but these neurones do not possess the oestrogen receptor. Based on indirect evidence, we hypothesized that oestrogen receptor-containing neurones in the ventromedial preoptic area (vmPOA) may be the initial step in a neuronal system whereby oestradiol suppresses GnRH secretion during the non-breeding season. To test this, three experiments were conducted using ovariectomized ewes receiving either empty or oestradiol-containing bilateral microimplants directed at the vmPOA or s.c. subcutaneous oestradiol-containing implants. In the first experiment, LH pulse frequency was measured on days 0, 1, 7 and 14 of treatment during seasonal anoestrus. In vmPOA oestradiol and s.c. oestradiol groups only, LH pulse frequency was suppressed on days 7 and 14, with maximal suppression evident by day 7. In the second experiment, this protocol was repeated during the breeding season, with LH pulses examined on days 0 and 7; LH pulse frequency did not change in any group. The third experiment tested if the effect of vmPOA oestradiol during anoestrus could be overcome by an injection of the dopamine-D2 receptor antagonist (-)-sulpiride. The vmPOA microimplants and s.c. oestradiol implants again suppressed LH pulse frequency and this was reversed by sulpiride in vmPOA oestradiol ewes. We conclude that oestradiol acts on cells in the vmPOA to stimulate a system involving dopamine neurones that inhibits GnRH/LH pulsatility in the anoestrous ewe.

Localized antimicrobial peptide expression in human gingiva

The stratified epithelia of the oral cavity are continually exposed to bacterial challenge that is initially resisted by innate epithelial factors and by the recruitment of neutrophils. Antimicrobial peptides from phagocytes and epithelia contribute to this antimicrobial barrier. Using antibodies and in situ hybridization, we explored antimicrobial peptide expression in the varied epithelia of the periodontium and in cultured gingival epithelial cells. In gingival tissue, mRNA for the beta-defensins, human beta-defensin 1 (hBD-1) and human beta-defensin 2 (hBD-2) was predominately localized in suprabasal stratified epithelium and the peptides were detected in upper epithelial layers consistent with the formation of the stratified epithelial barrier. In cultured epithelial cells, both hBD-1 and -2 peptides were detected only in differentiating, involucrin-positive epithelial cells, although hBD-2 required stimulation by proinflammatory mediators or bacterial products for expression. Beta-defensins were not detected in junctional epithelium (JE) that serves as the attachment to the tooth surface. In contrast, alpha-defensins and cathelicidin family member LL-37 were detected in polymorphonuclear neutrophils (PMNs) that migrate through the JE, a localization that persists during inflammation, when the JE and surrounding tissue are highly infiltrated with PMNs. Thus, the undifferentiated JE contains exogenously expressed alpha-defensins and LL-37, and the stratified epithelium contains endogenously expressed beta-defensins. These findings show that defensins and other antimicrobial peptides are localized in specific sites in the gingiva, are synthesized in different cell types, and are likely to serve different roles in various regions of the periodontium.