Hepatitis B and hepatitis C seroprevalence and risk behaviour among community-recruited drug injectors in North West Wales

We estimated the prevalence of markers of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection, and injecting risk behaviour, among community-recruited injecting drug users (IDUs) in North West Wales in 2001 and 2002. Sample collection was undertaken by trained current and former IDUs. Oral fluid samples (n = 153) were tested as part of the Unlinked Anonymous Prevalence Monitoring Programme ongoing survey of IDUs. Approximately 12% of the sample reported that they were currently in a drug treatment programme. Of the 153 samples screened 27% (95% CI 20%-34%, 41/153) were anti-HBc positive, and 23% (95% CI 16%-30%, 35/153) were anti-HCV positive. Sixteen per cent (95% CI 10%-22%, 25/ 153) of the samples were positive for both anti-HBc and anti-HCV. Of the subjects 15% (95% CI 9%-20%) knew they had been vaccinated against hepatitis B. Direct sharing of needles and syringes in the 28 days prior to interview was reported by 44% (95% CI 35%-54%), and sharing of any equipment including that used for drug preparation prior to injection was reported by 66% (95% CI 57%-76%). In North West Wales, syringe sharing is a common practice, and a high proportion of IDUs have been exposed to bloodborne viruses. Hepatitis B vaccination coverage within this population appears to be low and needs to be increased. Further efforts are needed to improve the availability of clean injecting equipment.

Successful treatment of a pancreatic pseudocyst by omentalisation in a dog

CASE HISTORY

A 3-year-old male Labrador retriever was presented with a history of dietary indiscretion followed by vomiting and abdominal pain.

CLINICAL FINDINGS AND TREATMENT

Abdominal ultrasonography revealed the presence of a fluid-filled cystic structure in the region of the pancreas. Flocculent, dark fluid was drained from the cystic structure during exploratory celiotomy prior to resection of the lateral cystic wall. Omentum was sutured into the cystic cavity to provide drainage and enhance immune response. A jejunostomy feeding tube was placed. Post-surgical care consisted of antibiotic therapy. The dog was clinically normal at 1 and 7 months post-operatively and the pancreas appeared normal on final ultrasonographic examination.

CLINICAL RELEVANCE

This case describes the use of omentum to provide physiological drainage of a pancreatic pseudocyst. This surgical technique may help clinicians manage patients with this condition in the future.

Cranial cruciate ligament injury in the dog: pathophysiology, diagnosis and treatment

Cranial cruciate ligament (CCL) disease in the dog is a multifactorial complex problem that requires a thorough understanding of the biomechanics of the stifle joint to be understood. Successful treatment of rupture of the CCL should be based on managing underlying anatomical and conformational abnormalities rather than attempting to eliminate the tibial cranial drawer sign. The cranial and caudal cruciate ligaments, the patella ligament and quadriceps mechanism, the medial and lateral collateral ligaments, the medial and lateral menisci and the joint capsule provide stability of the joint and load-sharing. The function of the stifle is also significantly influenced by the musculature of the pelvic limb. An active model of biomechanics of the stifle has been described that incorporates not only the ligamentous structures of the stifle but also the forces created by weight-bearing and the musculature of the pelvic limb. This model recognises a force called cranial tibial thrust, which occurs during weight-bearing, and causes compression of the femoral condyles against the tibial plateau. In middle-aged, large-breed dogs, forces acting on the CCL together with conformation-related mild hyperextension of the stifle and slightly increased tibial plateau slopes are suspected to cause progressive degeneration of the ligament. Palpation of craniolateral stifle laxity has become pathognomonic for CCL rupture; however, chronic periarticular fibrosis, a partial CCL rupture, and a tense patient, may make evaluation of instability of the stifle difficult. Surgical treatment is broadly separated into three groups: intracapsular, extracapsular, and tibial osteotomy techniques. Tibial osteotomy techniques do not serve to provide stability of the stifle but rather alter the geometry of the joint to eliminate cranial tibial thrust such that functional joint stability is achieved during weight-bearing. Visualisation of both menisci is a critical aspect of CCL surgery, irrespective of the technique being performed. Regardless of the surgical technique employed, approximately 85% of dogs show clinical improvement. However, many of these dogs will demonstrate intermittent pain or lameness. Post-operative management is an integral part of the treatment of CCL rupture, and significant benefits in limb function occur when formalised post-operative physiotherapy is performed.

The effect of maternal prolactin infusion during pregnancy on fetal adipose tissue development

The present study determines whether maternal administration of prolactin (PRL) to dams promotes the abundance of the brown adipose tissue-specific uncoupling protein-1 (UCP1) in fetal and neonatal rat pups. Recombinant PRL (24 micro g/kg per day), or an equivalent volume of saline, were infused into dams (n=19 per group) throughout pregnancy from 12 h after mating. Interscapular brown adipose tissue was sampled either from fetuses at 19.5 days of gestation (term=21.5 days) or from neonatal rat pups at approximately 18 h after birth. The abundance of UCP1 was determined by immunoblotting on adipose tissue samples from individual pups and pooled from groups of pups. This analysis was complemented by immunocytochemistry on representative adipose tissue samples. Maternal PRL infusion resulted in a greater abundance of UCP1 in fetal rats at 19.5 days of gestation (control: 97.2+/-8.4% reference; PRL: 525.6+/-74.4% reference; P<0.001) and in neonates 18 h after birth. In contrast, the abundance of the outer mitochondrial membrane protein voltage-dependent anion channel was unaffected by PRL. Neonatal adipose tissue sampled from pups born to PRL-infused dams possessed fewer lipid droplets, but more UCP1, as determined by immunocytochemistry. Fetal, but not maternal, plasma leptin concentrations were also increased by maternal PRL administration. In conclusion, as rats are altricial, and the potential thermogenic activity of brown adipose tissue develops over the first few days of postnatal life, these changes prior to, and at the time of, birth implicate PRL in fetal and neonatal adipose tissue maturation.

Statin use, hyperlipidaemia, and the risk of breast cancer

Hydroxymethyl glutaryl coenzyme A inhibitors ("statins") are carcinogenic in rodents and an increased incidence of breast cancer was reported among pravastatin users in one randomised trial. We conducted a case-control study in the General Practice Research Database to evaluate the risk of breast cancer among 50- to 79-year old women treated with statins for hyperlipidaemia. Case and control women were matched by age, general practice, duration of prescription history in the General Practice Research Database, and index date. Adjusting for history of benign breast disease, body mass index, and use of hormone replacement therapy, women currently treated with statins had an estimated relative risk for breast cancer of 1.0 (95% confidence interval 0.6-1.6) compared to women without hyperlipidaemia. Untreated hyperlipidaemia was associated with an increased risk of breast cancer (estimated relative risk 1.6; 95% confidence interval 1.1-2.5). The estimated relative risk among women currently receiving only non-statin lipid-lowering drugs was similar to that of women with untreated hyperlipidaemia (1.8; 95% confidence interval 0.9-3.4). We found no evidence for an increasing trend in breast cancer risk with increasing duration of statin use (median duration 1.8 years, maximum 8.6 years).

Unmodified and phosphorylated prolactin and gamma delta T cell development and function

This manuscript discusses our studies to date concerning the effects of unmodified prolactin (PRL) and phosphorylated PRL on immune function. Most of the discussion refers to effects of changing the ratio of these two forms in maternal PRL on gamma delta T cell development in rat pups in utero, but limited experiments where adult animals have been directly treated are also discussed. The manuscript begins with some general background on gamma delta T cells and the different forms of PRL and then proceeds to a discussion of experimental findings. Results demonstrate that the ratio of unmodified to phosphorylated PRL during rat pregnancy is crucial to normal epidermal gamma delta T cell development in the pup thymus. Elevation of phosphorylated PRL in the dams, by administration of a recombinant molecular mimic of phosphorylated PRL, produces a defect in epidermalgamma delta T cell seeding and subsequent function in the offspring. In contrast, a functional defect is not seen for uterine gamma delta T cells in the offspring, a finding likely reflective of the continued availability of precursors to these cells after the fetal period. Preliminary results from treatment of the NZB/NZW mouse model of lupus with the two forms of PRL suggest opposing effects of unmodified and phosphorylated PRL on one measure of the disease.

Cerebral circulation in REM sleep: is oxygen a main regulating factor?

In the transition from NREM to REM sleep, as in other instances of brain activation, a marked increase in cerebral blood flow and glucose uptake is observed, together with a lesser increase in O2 uptake. Brain activation also entails an increase in capillary PO2 and lactate production. The hypothesis of saturation of the oxidative machinery was advanced to explain anaerobic glycolysis and lactate production in the presence of high PO2, but data are available that cannot be explained by this hypothesis: hypoxic spots exist in the brain, augmenting in arterial hypoxia and disappearing in arterial hyperoxia, while tissue [H+] lowers as arterial PO2 increases beyond 100 mmHg. Additional hypotheses are thus required. We suggest that O2 diffusion limitation exists in the brain: microregions lying at mid-distance between capillaries may become hypoxic and partly resort to anaerobic glycolysis. These microregions are thought to enlarge with increasing metabolic rate or arterial hypoxia and give rise to vasodilatatory signals regulating local blood flow. REM sleep time is strongly reduced by hypoxic and increased by hyperoxic atmosphere, in accordance with the existence of an O2 diffusion limitation. Any pathological decrease in arterial PO2 and/or O2 delivery creates a specific risk in REM sleep.

Discontinuation of postmenopausal hormone therapy in a Massachusetts HMO

Long-term postmenopausal hormone therapy alleviates menopausal symptoms, decreases women's risk of osteoporosis and has been shown to reduce cardiovascular morbidity and mortality in more than 30 observational studies. However, nearly half of all women initiating hormone therapy discontinue within the first year. This study was conducted to determine the rate and predictors of hormone therapy discontinuation in a clinical practice setting. We identified 992 women aged 45-59 who began hormone therapy between 1993 and 1995 in a Massachusetts health maintenance organization. Women were followed 2 years from the day they filled a prescription for estrogen. 53% discontinued hormone therapy by the end of the first year and one-fifth stopped after the first prescription. A prescription from a gynecologist (RR = 0.82, 95% CI: 0.68, 0.99) and a mammogram a year prior to initiation (RR = 0.75, 95% CI: 0.63, 0.89) were associated with a lower rate of discontinuation. Women who were using monoamine oxidase inhibitors (MAOI) or selective serotonin reuptake inhibitors (SSRI) antidepressants 3 months prior to initiation (RR = 2.07, 95% CI: 1.26, 3.39) or who had been enrolled in the health plan for less than 3 years (RR = 1.33, 95% CI: 1.10, 1.62) had an increased risk of discontinuing hormone therapy. The year a woman entered the cohort was also associated with a higher rate of discontinuation (RR = 1.40, 95% CI: 1.14, 1.74 for 1994 and RR = 1.95, 95% CI: 1.52, 2.50 for 1995). The results indicate that long-term hormone therapy use is uncommon in clinical practice, particularly when a woman or her physician attempts to use hormone therapy as an alternative to antidepressant therapy, and that the rates of discontinuation of hormone therapy were rising rapidly in the mid-1990s.

Left ventricular stroke volume in the fetal sheep is limited by extracardiac constraint and arterial pressure

1. Extracardiac constraint and sensitivity to arterial pressure may be critical factors that limit the functional reserves of the developing fetal heart in utero. We hypothesise that extracardiac constraint is the predominant factor that limits fetal stroke volume (SV). To test this hypothesis we studied six chronically instrumented fetal sheep to determine the relative roles that extracardiac constraint and arterial pressure play in determining left ventricular (LV) function. 2. Pregnant ewes (128-131 days gestation, term = 147 days) were anaesthetised (5 mg kg(-1) Propofol I.V., then 1.5 % halothane, 50 % O(2), balance N(2)O by inhalation) and instrumented using sterile surgical techniques to record LV end-diastolic pressure (P(lved)), aortic pressure (P(ao)), pericardial pressure (P(per)), and LV SV. 3. After a minimum of 72 h recovery, LV function was assessed by altering fetal blood volume to vary P(lved). Ventricular function curves were generated using two measures of ventricular function, SV and stroke work index (SWI = SV x P(ao)), and two measures of ventricular filling, P(lved) and LV end-diastolic transmural pressure (P(lved,tm) = P(lved) - P(per)). 4. Although decreasing P(lved) from the resting level decreased SV, increasing P(lved) from the resting level did not increase SV because the ventricular function curve plateaued. This plateau was not explained solely by an increase in aortic pressure, as the plateau remained present in the SWI versus P(lved) curve. When extracardiac constraint was accounted for (SV against P(lved,tm)), the plateau was largely eliminated (approximately 80 %). The remaining portion of the plateau (approximately 20 %) was eliminated when both extracardiac constraint and arterial pressure were accounted for (SWI versus P(lved,tm)). 5. Thus, the major limitation upon LV function in the near-term fetus results from extracardiac constraint limiting ventricular filling while, at the same time, a much smaller limitation arises from increasing arterial pressure.

A molecular mimic of phosphorylated prolactin markedly reduced tumor incidence and size when DU145 human prostate cancer cells were grown in nude mice

Others have demonstrated the presence of an autocrine prolactin (PRL) growth loop in the normal human prostate. In this study we have used three human prostate cancer cell lines but have focused on the androgen-independent human prostate cancer cell line, DU145, to ask: (a) whether this autocrine growth loop is maintained beyond the loss of androgen sensitivity in the progression of prostate cancer; and (b) whether interruption of this growth loop by a PRL receptor antagonist, an S179D mutant PRL, could inhibit the formation of DU145-derived tumors. The autocrine loop was examined in most detail in the DU145 cell line but was demonstrated to be functional in all three of the lines by the reversible inhibition of growth in vitro by the S179D PRL receptor antagonist. To investigate the effect of S179D PRL on the growth of DU145 tumors in nude mice two sets of experiments were performed. In the first set, Alzet minipumps containing no PRL, wild-type (WT) PRL, or the S179D PRL (the last two delivering 4.56 microg/24 h and 4.26 microg/24 h, respectively), were implanted s.c. on day 1. On day 4, 5 x 10(6) DU145 cells were injected s.c. in the hindquarter. On day 22, the animals were killed, tumors were removed, measured, and subsequently fixed and processed for histological confirmation of tumor formation. The incidence of tumors in the no-PRL control group was 9/11 animals (82%). In the animals treated with WT PRL, the incidence was 8/10 (80%), whereas in the animals treated with the S179D PRL, the incidence was markedly reduced to 3/11 (27%). Although WT PRL had no effect on the incidence of tumors, the average size of the tumors increased from 25.8 +/- 5.99 mm(3) in controls to 66.66 +/- 18.06 mm(3) in WT PRL-treated animals. In the second set of experiments, 5 x 10(6) DU145 cells were injected on day 1. On day 18, Alzet minipumps containing no PRL, WT PRL, or S179D PRL were implanted. On day 42, the animals were killed and the tumors processed as before. S179D PRL caused a reduction in tumor size from 1731 +/- 283 mm(3) in the no-PRL controls to 1031 +/- 295 mm(3), whereas WT PRL slightly increased the size to 2118 +/- 630 mm(3). We conclude that PRL is used as an autocrine growth factor by human prostate cancer cells both in vitro and in vivo and that interruption of this growth loop in vivo inhibits tumor initiation and the growth of well-established tumors.

Pattern recognition in health insurance claims databases

Information in claims databases resides in data patterns rather than in data elements. Finding this information requires new terminology, a willingness to pose questions of form rather than specific hypotheses, and a quality control system that elevates the correctness of data relations above the validity of single facts. The language of claims data is a newspeak of CPT (Current Procedural Terminology), HCPCS (Health Care Financing Agency Common Procedure Coding System), ICD (International Classification of Disease), and NDC (National Drug Codes) for pharmaceutical codes. The techniques of pattern discovery are really ways of asking the data for classes of relations, and they vary in their reliance on external information. Sometimes, the question is entirely constrained by preceding factors. Other times we may recast the natural history of disease into a claims context and ask the data to give us the shape of disease evolution. We can use highly automated systems to evaluate the relations between prespecified factors, or empirical techniques to search out common relations that we have not specified in advance. Using massive data sets requires that quality control corresponds to the nature of the high-level information that we derive from large databases.

Lower prolactin bioactivity in unmedicated schizophrenic patients

In previous work, prolactin (PRL) abnormalities of a lower bioassay (BA) to radioimmunoassay (RIA) ratio were found in schizophrenic patients. This line of research was extended in seven male patients with schizophrenia who were neuroleptic-free; seven male control subjects were also studied. PRL values were assessed by RIA and Nb(2) BA techniques. The schizophrenic group had a significantly lower PRL BA as compared to normal controls and a lower PRL ratio of BA/RIA. The lower ratio is consistent with an earlier finding and suggests that schizophrenic patients have different molecular forms of PRL than control subjects. This difference could be due to a disordered tuberoinfundibular dopamine system or the long-term effects of neuroleptic medications.

Antidepressant use and the risk of breast cancer: a non-association

OBJECTIVE

Animal studies have suggested that some antidepressant medications may act as breast tumor promoters and recent epidemiologic studies of antidepressant use and breast cancer outcomes in humans have also reported such associations.

DESIGN

Retrospective cohort study.

STUDY POPULATION

38,273 women who filled a prescription for any of a number of antidepressants and 32,949 who filled a prescription for any other medication during 1989-1991; all were > or =20, enrolled in Medicare, Medicaid or the Pharmaceutical Assistance to the Aged and Disabled (PAAD) programs of New Jersey, and free of evidence of breast cancer.

DATA COLLECTION

Antidepressant use was assessed over a period lasting up to 24 months. Subjects were followed for a maximum of 7.5 years; those who had a first diagnosis of breast cancer in the New Jersey Cancer Registry at least 3 months after their index date were considered incident breast cancer cases. Other covariates, including demographic, clinical, and health care utilization variables were also assessed. MAIN OUTCOME OF INTEREST: Adjusted hazard ratio (HR) of developing breast cancer, based on multivariable proportional hazards models.

RESULTS

Use of antidepressants was unrelated to the development of breast cancer (adjusted HR = 1.04; 95% CI 0.87-1.25). No elevated risks were found for specific antidepressants, including agents found to be breast tumor promoters in animal studies, as well as drugs thought to be associated with breast cancer in prior epidemiologic studies. There was no suggestion that breast cancer risks were increased with more intensive use of antidepressants or that antidepressant use is associated with a more severe stage of cancer at diagnosis.

CONCLUSIONS

Despite recent reports from much smaller epidemiologic studies or laboratory animals, these results provide reassurance that antidepressant use is not associated with the development of breast cancer.

Nitric oxide inhibition abolishes sleep-wake differences in cerebral circulation

Nitric oxide (NO), being produced by active neurones and also being a cerebral vasodilator, may couple brain activity and blood flow in sleep, particularly during active sleep (AS), which is characterized by widespread neural activation and markedly elevated cerebral blood flow (CBF) compared with quiet wakefulness (QW) and quiet sleep (QS). This study examined CBF and cerebral vascular resistance (CVR) in lambs ( n = 6) during spontaneous sleep-wake cycles before and after infusion of N ω-nitro-l-arginine (l-NNA), an inhibitor of NO synthase. l-NNA infusion produced increases in CVR and decreases in CBF during all sleep-wake stages, with the greatest changes occurring in AS (ΔCVR, 88 ± 19%; ΔCBF −24 ± 8%). The characteristic CVR and CBF differences among AS, QS, and QW disappeared within 1–3 h ofl-NNA infusion, but had reappeared by 24 h despite persisting cerebral vasoconstriction. These experiments show that NO promotes cerebral vasodilatation during sleep as well as wakefulness, particularly during AS. Additionally, NO is the major, although not sole, determinant of the CBF differences that exist between sleep-wake states.

Right atrial pressure as measure of ventricular constraint in newborn lambs

Although the lungs and pericardium constrain the heart and limit cardiac output, no method exists to assess this constraint in sick newborns. We hypothesize that a useful estimate of ventricular constraint may be obtained by measuring right atrial pressure (P(RA)) in the newborn. To test this hypothesis, we measured P(RA), thoracic inferior vena caval pressure (P(IVC); saline-filled catheters), and ventricular constraint (pericardial pressure, P(PER); liquid-containing balloon) in 4-wk-old (neonatal, n = 12) and 3-day-old (newborn, n = 6) anesthetized lambs. The measurements were made while LV filling pressure was altered (0-20 mmHg) and while positive end-expiratory pressure (PEEP) was maintained at 2.5 or 15 cmH2O. In all of the lambs, a strong linear relationship (r) existed between P(RA) and P(PER) (P(RA) = 1.19 P(PER) + 0.0, r = 0.99) and between P(IVC) and P(PER) (P(IVC) = 1.24 P(PER) + 0.1, r = 0.99; PEEP of 2.5 cmH2O). Similar relationships were also observed with increased PEEP (P(RA) = 1.29 P(PER)-1.2, r = 0.98 and P(IVC) = 1.32 P(PER)-1.2, r = 0.97). Because P(RA) provides an accurate measure of ventricular constraint in the normal lamb, it may be a useful measure of ventricular constraint in the sick newborn.

Neural tube defects in relation to use of folic acid antagonists during pregnancy

Periconceptional folic acid supplementation reduces the risk of neural tube defects (NTDs). To determine whether periconceptional exposure to folic acid antagonists (FAAs) might therefore increase the risk of NTDs, the authors examined data from an ongoing case-control study of birth defects (1979-1998) in the United States and Canada. They compared data on 1,242 infants with NTDs (spina bifida, anencephaly, and encephalocele) with data from a control group of 6,660 infants with malformations not related to vitamin supplementation. Mothers were interviewed within 6 months of delivery about demographic, reproductive, medical, and behavioral factors and about medication use. The adjusted odds ratios of NTDs related to exposure to FAAs (including carbamazepine, phenobarbital, phenytoin, primidone, sulfasalazine, triamterene, and trimethoprim) during the first or second months after the last menstrual period, compared with no use in either month, were 2.8 (95% confidence interval: 1.7, 4.6) for FAAs as a group, 4.8 (95% confidence interval: 1.5, 16.1) for trimethoprim (based on five exposed cases), and 6.9 (95% confidence interval: 1.9, 25.7) for carbamazepine (six exposed cases). These results are adjusted for region, interview year, periconceptional folic acid supplementation, maternal age, weight, education, and infections early in pregnancy. These findings suggest that a number of FAAs may increase NTD risk, and they provide estimates of risk for selected drugs.

Contraindicated medications dispensed with cisapride: temporal trends in relation to the sending of 'Dear Doctor' letters

PURPOSE

'Dear Doctor' letters alert the prescribing community of drug labeling changes that contain new contraindications, warnings, adverse reactions, and precautions. There has been little assessment of the impact of these letters. We quantified the impact of two 'Dear Doctor' letters concerning interactions between cisapride and a series of drugs. A letter in 1995 described a risk of prolonged QT intervals and serious ventricular arrhythmia in patients who received macrolide antibiotics and imidazole antifungals in conjunction with cisapride. A June 1998 letter that expanded the list of contraindicated comedications had wider distribution than an earlier one, was accompanied by substantial Internet and media coverage, and was complemented by an effort to inform large pharmacy dispensing information organizations of the warnings against concurrent use of the named drugs.

METHODS

Health plan members with one or more outpatient pharmacy claims for cisapride during the period 1 January 1995 through 31 May 1999 were identified among members of a large New England health insurer. A retrospective review of concurrent and nearly concurrent dispensings of cisapride and contraindicated comedications was undertaken in the automated pharmacy claims data using both graphical and statistical time-series analysis. We tabulated by month the fraction of cisapride dispensings that occurred in close temporal relation to dispensings of contraindicated comedications. Codispensings that occurred on the same day were taken as the most direct measure of prescriber responsiveness to the letters. Codispensings that occurred in windows of plus or minus 2 weeks (29 day window) and plus or minus 4 weeks (57 day window) were taken as measures of possible simultaneous consumption. Among overlapping dispensings, we counted the proportion dispensed by the same pharmacy. Time series regression analysis of secular, seasonal, and step-effects was conducted.

RESULTS

There was a steady decline in codispensing of cisapride and contraindicated medicines, and a pronounced seasonal effect, arising principally from the seasonal use of macrolide antibiotics. Against this background, the isolated Dear Doctor letter of October 1995 had no discernible effect on prescribing practices. The 1998 letter and surrounding activity, by contrast, were followed by a 66% decline in same-day dispensings and a smaller, but still pronounced decline in dispensings in the wider time windows. For most codispensings of contraindicated medications with cisapride, both medications came from the same pharmacy.

CONCLUSIONS

Publicity and direct intervention with dispensing pharmacies may be an important supplement to Dear Doctor letters when the goal is to eliminate the codispensing of drugs that should not be taken together.

Side effects and sociobehavioral factors associated with the discontinuation of hormone therapy in a Massachusetts health maintenance organization

OBJECTIVE

To identify sociobehavioral factors and side effects associated with the discontinuation of postmenopausal hormone therapy in a clinical practice setting

DESIGN

A total of 816 women aged 45-59 who began hormone therapy between July 1993 and June 1995 in a Massachusetts health maintenance organization were followed for 2 years from the day they received a prescription for estrogen. This cohort has been previously studied for health, treatment, and demographic determinants of hormone therapy discontinuation. In March 1999, these women were mailed a questionnaire containing closed and open-ended questions. A total of 449 women (55%) completed the survey. Discrete-time hazards models were used to identify determinants of discontinuation, controlling for medical predictors of survey nonresponse.

RESULTS

Women separated from their partners when they initiated hormone therapy (relative risk [RR] of discontinuation = 3.42; 95% confidence interval [CI] = 1.09, 10.73) and women with a body mass index greater than 29.0 (RR = 1.62; 95% CI = 1.18, 2.23) were more likely to discontinue. Women who had ever used oral contraceptives were less likely to discontinue hormone therapy (RR = 0.70; 95% CI = 0.51, 0.98). After women began using hormone therapy, those who experienced irregular bleeding (RR = 1.58; 95% CI = 1.08, 2.31), edema (RR = 2.18; 95% CI = 1.42, 3.34), or abdominal cramps and pelvic pain (RR = 2.42; 95% CI = 1.46, 4.02) while using hormones were more likely to discontinue. The effect of edema and abdominal cramps on the rate of discontinuation was greatest during the first 6 months of use. Women who adjusted their progestin schedule on their own were four times more likely than other women to discontinue hormones (RR = 4.18; 95% CI = 2.20, 7.94). The use of alternative therapies was not statistically associated with discontinuation.

CONCLUSIONS

Women who report therapeutic benefits from hormone therapy are more likely to continue using hormones long-term. The experience of certain side effects, especially during the first few months of hormone use, strongly affects whether women continue using hormone therapy.

Finding incident breast cancer cases through US claims data and a state cancer registry

OBJECTIVE

With the increasing availability of automated health-care data, new methods are available to screen large populations for the presence of cancer diagnoses. However, it is crucial to evaluate how completely incident cancer cases can be ascertained using these data sources.

METHODS

We used capture-recapture techniques to estimate the total number of incident breast cancer cases occurring within one state during a 3-year period. We then compared the ascertainment of these cases by the following two data sources: claims for breast cancer surgery recorded in Medicaid and Medicare data vs a cancer registry in the same state.

RESULTS

Medicaid-Medicare breast cancer surgery claims identified 68% of the total estimated number of incident breast cancer cases while cancer registry data identified 78%. Case ascertainment improved markedly to 91% when both registry and Medicare-Medicaid data sources were used together. The sensitivity of ascertainment was lower for Medicaid-Medicare data among those aged under 65 and non-white; ascertainment was lower for the registry among women who were aged under 65, poor, and non-white.

CONCLUSIONS

Combining health insurance claims data with a population-based cancer registry improved the identification of incident cases of breast cancer, and may be particularly useful among demographic groups found to be at highest risk of under-ascertainment such as younger women, the poor, and racial minorities.

Administration of unmodified prolactin (U-PRL) and a molecular mimic of phosphorylated prolactin (PP-PRL) during rat pregnancy provides evidence that the U-PRL:PP-PRL ratio is crucial to the normal development of pup tissues

During rat pregnancy initial high concentrations of prolactin (PRL) decline by about day 9, concomitant with an increase in the ratio of unmodified to phosphorylated PRL. The physiological significance of both the decline in total PRL and the change in ratio of the two PRLs is unknown. To test the importance of each, either unmodified PRL (U-PRL) or a molecular mimic of phosphorylated PRL (PP-PRL) were continuously administered to rats throughout pregnancy. A dose of 6 microg/24 h resulted in circulating concentrations of 50 ng/ml of each administered PRL and had little effect on the pregnancy itself. After birth, pups were killed and various tissues examined. In the pup lungs, exposure to additional PP-PRL caused a reduction in epithelial integrity and an increase in apoptosis, whereas exposure to additional U-PRL had beneficial, anti-apoptotic effects. In the heart, PP-PRL caused an apparent developmental delay, whereas U-PRL promoted tissue compaction. In the blood, U-PRL increased the number of mature red blood cells at the expense of white blood cell production. Within the white blood cell population, myelopoiesis was favored at the expense of lymphopoiesis. PP-PRL, in contrast, had a less dramatic influence on the hematopoietic compartment by promoting red blood cell maturation and granulocyte production. In the thymus, exposure to PP-PRL caused accumulation of apoptotic thymocytes in enlarged glands, whereas exposure to U-PRL resulted in smaller thymi. In the spleen, exposure to U-PRL increased cellularity, with the majority of cells belonging to the erythroid series - a finding consistent with increased red blood cells in the circulation. Exposure to PP-PRL was without discernible effect. In all of these tissues, the contrasting effects of the two PRLs indicate that the absolute concentration of PRL is not crucial, but that the ratio of U-PRL to PP-PRL has a profound effect on tissue development. In brown fat, both PRL preparations decreased the number of lipid droplets. This result is therefore probably a consequence of the increase in total PRL. The results of this study attest to the importance of the U-PRL:PP-PRL ratio normally present during pregnancy and have provided clues as to the possible pathogenesis of a variety of neonatal problems.

On the evaluation of drug benefits policy changes with longitudinal claims data: the policy maker's versus the clinician's perspective

Cost containment in pharmaceutical-benefit plans are often controversially debated for their potential of unintended consequences on health and overall expenditures. Thorough evaluations are needed but hypotheses and design considerations are complex. Our objective is to provide a structured framework for the evaluation of drug-benefit changes using longitudinal claims data. Differential cost sharing (DCS) will serve as a recent example. Benefit-plan managers are mainly interested in the overall performance of their plan. In a policy model, any observed policy-related effects may be compared with what would have happened had the intervention not been implemented by extrapolating the pre-policy trend from the same patients. These estimates will reflect the global consequences of the policy maker's decision. However, such estimates represent summary effects of benefits and harms, separately identifiable in those complying with the intended policy and those not complying. Results from a policy model apply only to a specific policy implementation and tend to underestimate effects when non-compliance is high. Clinical-decision makers and patients, by contrast, are interested in the consequences of patients' actual compliance to the policy. A clinical model assesses the effects of DCS depending on the actual treatment in contrast to the treatment intended by the policy. However, this model must sometimes make, unprovable assumptions about the appropriate control of selection factors. In conclusion, both policy and clinical models should be tested with a clear understanding of their perspectives, hypotheses, and interpretations, using quasi-experimental time-series designs to evaluate the effects of drug cost-containment policies.

Hepatitis B vaccination and the risk of multiple sclerosis

BACKGROUND

Reports of multiple sclerosis developing after hepatitis B vaccination have led to the concern that this vaccine might be a cause of multiple sclerosis in previously healthy subjects.

METHODS

We conducted a nested case-control study in two large cohorts of nurses in the United States, those in the Nurses' Health Study (which has followed 121,700 women since 1976) and those in the Nurses' Health Study II (which has followed 116,671 women since 1989). For each woman with multiple sclerosis, we selected as controls five healthy women and one woman with breast cancer. Information about hepatitis B vaccination was obtained by means of a mailed questionnaire and was confirmed by means of vaccination certificates. The analyses included 192 women with multiple sclerosis and 645 matched controls and were conducted with the use of conditional logistic regression.

RESULTS

The multivariate relative risk of multiple sclerosis associated with exposure to the hepatitis B vaccine at any time before the onset of the disease was 0.9 (95 percent confidence interval, 0.5 to 1.6). The relative risk associated with hepatitis B vaccination within two years before the onset of the disease was 0.7 (95 percent confidence interval, 0.3 to 1.8). The results were similar in analyses restricted to women with multiple sclerosis that began after the introduction of the recombinant hepatitis B vaccine. There was also no association between the number of doses of vaccine received and the risk of multiple sclerosis.

CONCLUSIONS

These results indicate no association between hepatitis B vaccination and the development of multiple sclerosis.

Age-related differences in the distortion of the sheep lung in response to localised pleural stress

In order for diastolic filling to occur, the heart must displace the lung. Given the changes in lung structure and compliance that follow birth, we sought to determine whether the neonatal lung resists neighbouring structures encroaching into its space more than the adult lung and whether the lung surface making up the cardiac fossa resists distortion more than the lateral surface does. Pleural distortions, induced by applied pressures (Pappl) of 20-120 g cm(-2) at airway pressures (Paw) of 2.5-15 cm H2O, were recorded in isolated lungs of adult, neonatal (4-week-old) and newborn (1-week-old) sheep. The depth of pleural distortion increased (P < 0.05, ANOVA) with increasing Pappl in all lungs. Adult lungs were significantly more distortable than newborn and neonatal lungs (P < 0.05). As Paw increased, the distortability of the adult lung decreased progressively (P < 0.05) while the distortability of the newborn and neonatal lung remained constant at Paw of 2.5 and 5 cm H2O. Adult lungs also differed from newborn and neonatal lungs in that the cardiac fossal surface was significantly less distortable than the lateral surface. As newborn and neonatal lungs are less easily distorted than adult lungs, the potential for the lungs to limit cardiac filling is greater in the newborn and neonate than in the adult.