GENDER DIFFERENCES IN BLEEDING PROBLEMS AND IMPLICATIONS FOR THE ASSESSMENT OF A BLEEDING DISORDER

Background: The value of gender-specific questions in assessing patients for bleeding problems is not well established, nor is the impact of bleeding on sexual and reproductive health. Methods: We administered the CHAT (clinical history assessment tool) to 256 females and 66 males referred for bleeding problems, and 67 female and 32 male healthy controls. This detailed bleeding history questionnaire included questions about sexual health, blood in semen, and bleeding with circumcision, menses, pregnancies, and childbirth. A diagnosis for each patient was established by independent medical record review. The prevalence of symptoms among patients and controls was compared. Results: 80% of patients had bleeding disorders (205 women, 54 men). Men with bleeding disorders did not have significantly increased intercourse-related bleeding, bleeding affecting their sex life, or gender-specific bleeding. Women with bleeding disorders had significantly increased intercourse-related bleeding and bleeding affecting their sex life. They also had significantly increased risks of prolonged menses, menses interfering with lifestyle, and menses requiring medical or surgical therapy (all p values < 0.001). Women with bleeding disorders were more concerned about pregnancy and delivery because of bleeding (p=0.0001), and 38% had been told by a doctor not to become pregnant. Yet they did not have increased risks for pregnancy loss or bleeding during pregnancy (p values > 0.1) and had similar numbers of offspring as controls (mean 2.0 vs.1.7). Conclusion: Gender has an important impact on the manifestations, diagnosis and management of common bleeding disorders. Detailed questions about gender-specific bleeding are useful in assessing women with possible bleeding disorders, as they are at greater risk for bleeding that negatively impacts their sexual and reproductive health.

Handheld computers and paper diaries for documenting the use of factor concentrates used in haemophilia home therapy: a qualitative study

A recently published randomized controlled trial (RCT) showed that adherence to infusion diary record keeping was improved by the use of handheld computers. In this study, attitudes to record keeping were explored and patient preferences regarding the method of recording determined for the patients who participated in the trial. Qualitative study consisting of individual semi-structured interviews with 20 severely affected patients with haemophilia who participated in an RCT. Individuals were purposefully sampled based on their recent method of record keeping and whether child or adult. Analysis employed a constant comparative method to identify key themes from the data. Most individuals (19 of 20, 95%) considered record keeping to be important. They readily identified reasons to keep records: to benefit themselves, their families, clinical staff, product distributors and manufacturers. Keeping records helps them: feel a part of the health care team; have confidence they would be notified of product recalls; review their past history; improve their ability to advocate for themselves and improve communication among all parties. Record keeping, particularly when using paper diaries, can be burdensome and a challenge to maintain consistently. All 10 individuals (100%) who had used both paper diaries and handheld computers preferred the latter. Most patients understand that record keeping can be of benefit to them. Clinics can use this knowledge to inspire other patients by developing educational programmes that de-emphasize authority. In addition, given the evidence of both patients' preference for handheld computers, and the effectiveness of this approach documented in an RCT, switching to handheld computers is likely to improve record keeping.

Comparing hand-held computers and paper diaries for haemophilia home therapy: a randomized trial

Treatment of severe haemophilia with factor concentrates is by self-infusion in the home. Adherence to record keeping on paper diaries is poor. A randomized-controlled trial compared adherence with record keeping of paper diaries with hand-held computers. Forty-one individuals with severe haemophilia, were randomized to hand-held computers (n = 22) or paper diaries (n = 19) and followed for 6 months. About 86.2% (679 of 788) of infusions by patients in the computer group were in compliance with the data submission schedule compared with only 48.3% (358 of 741) of infusions by patients using paper diaries (P < 0.0001). The time intervals between infusions and the receipt of data were shorter in the computer group (median 0.25 vs. 25 days respectively, P < 0.0001). Reminder phone calls by the clinic were made less frequently to users of hand-held computers than to users of paper diaries (median one vs. five times, P < 0.0001). Accuracy of data was similar for both methods. Compliance with hand-held computers was superior to paper diaries. The clinic received data from hand-held computers mostly on the same day, and nurses could thereby provide clinical advice more effectively. Although hand-held computers did not result in increased accuracy, errors could be detected and corrected more rapidly. Electronic data can more easily be verified, analysed and summarized than that from paper diaries.

Prophylactic platelet transfusion for haemorrhage after chemotherapy and stem cell transplantation

BACKGROUND

Platelet transfusions are used in modern clinical practice to prevent and treat bleeding in thrombocytopenic patients with bone marrow failure. Although considerable advances have been made in platelet transfusion therapy in the last 30 years, some areas continue to provoke debate, especially the use of prophylactic platelet transfusions for the prevention of thrombocytopenic bleeding.

OBJECTIVES

To determine the optimal use of platelet transfusion for the prevention of haemorrhage (prophylactic platelet transfusion) in patients with haematological malignancies undergoing chemotherapy or stem cell transplantation.

SEARCH STRATEGY

Randomised controlled trials (RCTs) were searched for in the Cochrane Central Register of Controlled Trials (CENTRAL). Searching was also undertaken on the OVID versions of MEDLINE and EMBASE using an RCT search filter strategy.

SELECTION CRITERIA

Randomised controlled trials involving transfusions of platelet concentrates, prepared either from individual units of whole blood or by apheresis, and given prophylactically to prevent bleeding in patients with haematological malignancies and receiving treatment with chemotherapy and/or stem cell transplantation.

DATA COLLECTION AND ANALYSIS

All electronically derived citations and abstracts of papers identified by the review search strategy were initially screened for relevancy by one reviewer. Studies clearly irrelevant were excluded at this stage. The full text of all potentially relevant trials was then formally assessed for eligibility by two reviewers independently. Two reviewers completed data extraction independently. Missing data were requested from the original investigators, as appropriate. Disagreements were resolved by discussion with the other reviewers.

MAIN RESULTS

Eight completed published trials, with a total of 390 participants in the intervention groups and 362 participants in the control groups, were included in the review for further analysis. The eight studies were classified as: * three trials relevant to prophylactic platelet transfusions versus therapeutic platelet transfusions; * three trials relevant to prophylactic platelet transfusion with one trigger level versus prophylactic platelet transfusion with another trigger level; * two trials relevant to prophylactic platelet transfusion with one dose schedule versus prophylactic platelet transfusion with another dose schedule. The few reports of controlled trials addressing prophylactic versus therapeutic transfusions contained small numbers of patients and were all undertaken over 25 years ago. None of these three studies explicitly clarified whether the lack of a reported difference was a reflection of insufficient power in the trials. The findings of the meta-analyses for this group of three small studies must be interpreted with caution. In contrast, more contemporary trials addressed the question of what platelet count thresholds should apply for prophylactic transfusion; three identified studies broadly compared platelet transfusion thresholds of 10 versus 20 x 109/litre for different clinical groups of patients. There were no statistically significant differences between the groups with regards to mortality, remission rates, number of participants with severe bleeding events or red cell transfusion requirements. However, it was unclear whether the studies had sufficient power to demonstrate in combination non-inferiority in terms of safety of the lower threshold, 10 x 109/litre. Insufficient randomised trials have been undertaken to make clinically relevant conclusions about the effect of different platelet doses.

REVIEWERS' CONCLUSIONS

There are no reasons to change current practice but uncertainty about the practice of prophylactic transfusion therapy should be recognised, particularly in the light of concerns about the scenario that blood products, including platelets, could become an increasingly scarce resource in the future and for which adequate alternatives do not exist. Consideration should be given to developing adequately powered trials comparing strategies of prophylaxis versus therapeutic platelet transfusion.

An international study of the performance of sample collection from patients

BACKGROUND AND OBJECTIVES

Collection of a blood sample from the correct patient is the first step in the process of safe transfusion. The aim of this international collaborative study was to assess the frequency of mislabelled and miscollected samples drawn for blood grouping.

MATERIALS AND METHODS

Hospitals in 10 countries provided data on sample error rates during a period of at least 3 months, including the last quarter of 2001. Mislabelled samples were defined as those not meeting local criteria for acceptance by the laboratory. Miscollected samples [wrong-blood-in-tube (WBIT)] were defined as samples in which the blood group result differed from the result on file from prior testing. WBIT rates were corrected for the proportion of repeat samples and for undetectable errors occurring as a result of chance collection of blood from the wrong patient with the same ABO group. Participants also completed a questionnaire on current policies regarding sample collection.

RESULTS

A total of 71 hospitals completed surveys describing policies related to sample collection. Sixty-two hospitals provided usable data on the frequency of mislabelled and miscollected samples. Mislabelled and miscollected samples were common. Based on results from over 690,000 samples, the median hospital performance resulted in a rate for mislabelling of 1 in every 165 samples (6.1 per 1000; interquartile range 1.2-17 per 1000). The presence of national patient identification systems in Sweden and Finland was associated with rates of miscollected samples that were too low to estimate. Outside these nations, miscollected samples demonstrating WBIT occurred at a median rate of 1 in every 1986 samples (0.5 per 1000; interquartile range <0.3-0.9 per 1000). There was great variation worldwide in the reported frequency of mislabelled samples, probably resulting from variation in policies for sample acceptance. Miscollected samples occurred at a more constant rate.

CONCLUSIONS

The rate of mislabelled samples and miscollected samples is 1000-10,000-fold more frequent than the risk of viral infection. Rates of mislabelled samples and WBIT can be tracked as key indicators of performance of an important step in the clinical transfusion process. WBIT episodes represent important 'near-miss' errors. By providing baseline performance data for the collection of patient blood samples, this study may be useful in formulating future national standards of performance for sample collection from patients.

On-site continuing education: one big step for small laboratories

This report describes a new approach to continuing education which has been demonstrated to be effective in a number of small community hospital laboratories in a remote rural setting.

A Canadian hospital-based HIV/hepatitis C look-back notification program

OBJECTIVE

To describe the process used to notify pediatric patients who received transfusions of blood or blood products at our institution before donor blood was routinely screened for antibodies to HIV (1985) and hepatitis C virus (1990), and to evaluate the effectiveness of the notification program.

DESIGN

Patients who had received transfusions were identified through the hospital's medical records and the records from the Transfusion Medicine Laboratory. Patients were contacted by registered mail to provide notification of transfusion. A questionnaire was included with the notification to obtain information about the patient's awareness of the transfusion and whether he or she had undergone or planned to undergo testing for HIV and hepatitis C virus.

SETTING

Tertiary care university-affiliated teaching hospital in Hamilton, Ont.

PATIENTS

Patients 16 years of age or younger who had received blood products between February 1978 and November 1985. Patients who had received only albumin or immune serum globulin were not included as these products were not associated with viral transmission in Canada.

RESULTS

Notification letters were sent to 1546 patients. Of these letters 522 (33.8%) were returned undelivered. Of the 1024 patients contacted 493 (48.1%) responded to the questionnaire, of whom 157 (31.8%) were not aware of their transfusion. A total of 130 (26.4%) of the respondents had already undergone testing for HIV, and 342 (69.4%) indicated that they would undergo such testing as a result of the notification. In contrast, only 30 (6.3%) of 474 respondents had undergone testing for hepatitis C virus, but 425 (89.7%) indicated that they would undergo such testing. Overall, the patients' response to the notification was neutral or positive; however, a number of patients expressed dissatisfaction and anxiety.

CONCLUSIONS

The high proportion of patients who were unaware that they had undergone transfusion and who decided to undergo testing for HIV and hepatitis C virus as a result of notification supports the use of notification programs such as this one.

High-dose intravenous immune globulin and the response to splenectomy in patients with idiopathic thrombocytopenic purpura

BACKGROUND

High-dose intravenous immune globulin produces a temporary rise in the platelet count in patients with idiopathic thrombocytopenic purpura. Splenectomy may also be effective, but it is not possible to predict which patients will have a good response. We hypothesized that the response to intravenous immune globulin predicts the response to splenectomy.

METHODS

We studied retrospectively 30 patients with idiopathic thrombocytopenic purpura who had first been treated with immune globulin and then undergone splenectomy. The responses to the two treatments were classified on the basis of the platelet count as poor (<50,000 per cubic millimeter), good (50,000 to 150,000 per cubic millimeter), or excellent (>150,000 per cubic millimeter).

RESULTS

All nine patients who had poor responses to intravenous immune globulin also had poor responses to splenectomy at one year. Of the 21 patients with good or excellent responses to intravenous immune globulin, 19 had good or excellent responses to splenectomy.

CONCLUSIONS

Patients with idiopathic thrombocytopenic purpura who have good or excellent responses to intravenous immune globulin are likely to have good or excellent responses to splenectomy, whereas patients who have poor responses to intravenous immune globulin are unlikely to have good or excellent responses to splenectomy.

Splenectomy done during hematologic remission to prevent relapse in patients with thrombotic thrombocytopenic purpura

OBJECTIVE

To assess whether splenectomy done during hematologic remission reduces the relapse rate in patients with relapsing thrombotic thrombocytopenic purpura.

DESIGN

Consecutive case series.

SETTING

Tertiary care teaching hospital.

PATIENTS

6 consecutive patients seen during a 10-year period who had had one or more relapses of thrombotic thrombocytopenic purpura.

INTERVENTIONS

All patients had elective splenectomy while in hematologic remission and were followed after surgery for as long as 8.0 years.

MEASUREMENTS

Attack rates (events per year) were calculated for each patient from time of presentation to time of splenectomy and from time of splenectomy to January 1996.

RESULTS

A total of 26 episodes of thrombotic thrombocytopenic purpura occurred over 22.3 patient-years before splenectomy. After splenectomy, 3 acute episodes occurred over 22.7 patient-years. The attack rate (+/-1 SD) decreased from 2.3 +/- 2.0 events per year to 0.1 +/- 0.1 events per year.

CONCLUSION

In patients who have had one or more relapses of thrombotic thrombocytopenic purpura, splenectomy done during hematologic remission reduces the frequency of acute relapse and the resulting need for medical therapy.

Noninfectious adverse effects of blood transfusion in the neonate

There are many potential noninfectious complications that may be associated with the transfusion of blood products to the neonate. Most of these can be avoided by the careful preparation of the product according to current standards and the careful monitoring of the infant for metabolic changes during a transfusion. In general, there have been fewer systematic studies of transfusion-associated complications in neonates than in adults, possibly because of the difficulty of establishing a cause-effect relationship in the neonatal patient population. Such data, if available, would be useful for providing more effective blood product therapy to the neonate.

Basic statistics for clinicians: 4. Correlation and regression

Correlation and regression help us to understand the relation between variables and to predict patients' status in regard to a particular variable of interest. Correlation examines the strength of the relation between two variables, neither of which is considered the variable one is trying to predict (the target variable). Regression analysis examines the ability of one or more factors, called independent variables, to predict a patient's status in regard to the target or dependent variable. Independent and dependent variables may be continuous (taking a wide range of values) or binary (dichotomous, yielding yes-or-no results). Regression models can be used to construct clinical prediction rules that help to guide clinical decisions. In considering regression and correlation, clinicians should pay more attention to the magnitude of the correlation or the predictive power of the regression than to whether the relation is statistically significant.

Basic statistics for clinicians: 3. Assessing the effects of treatment: measures of association

In the third of a series of four articles the authors show the calculation of measures of association and discuss their usefulness in clinical decision making. From the rates of death or other "events" in experimental and control groups in a clinical trial, we can calculate the relative risk (RR) of the event after the experimental treatment, expressed as a percentage of the risk without such treatment. The absolute risk reduction (ARR) is the difference in the risk of an event between the groups. The relative risk reduction is the percentage of the baseline risk (the risk of an event in the control patients) removed as a result of therapy. The odds ratio (OR), which is the measure of choice in case-control studies, gives the ratio of the odds of an event in the experimental group to those in the control group. The OR and the RR provide limited information in reporting the results of prospective trials because they do not reflect changes in the baseline risk. The ARR and the number needed to treat, which tells the clinician how many patients need to be treated to prevent one event, reflect both the baseline risk and the relative risk reduction. If the timing of events is important--to determine whether treatment extends life, for example--survival curves are used to show when events occur over time.

Basic statistics for clinicians: 2. Interpreting study results: confidence intervals

In the second of four articles, the authors discuss the "estimation" approach to interpreting study results. Whereas, in hypothesis testing, study results lead the reader to reject or accept a null hypothesis, in estimation the reader can assess whether a result is strong or weak, definitive or not. A confidence interval, based on the observed result and the size of the sample, is calculated. It provides a range of probabilities within which the true probability would lie 95% or 90% of the time, depending on the precision desired. It also provides a way of determining whether the sample is large enough to make the trial definitive. If the lower boundary of a confidence interval is above the threshold considered clinically significant, then the trial is positive and definitive, if the lower boundary is somewhat below the threshold, the trial is positive, but studies with larger samples are needed. Similarly, if the upper boundary of a confidence interval is below the threshold considered significant, the trial is negative and definitive. However, a negative result with a confidence interval that crosses the threshold means that trials with larger samples are needed to make a definitive determination of clinical importance.

A comparison of two solid phase systems for antibody detection

Two solid phase methods of antibody detection, Capture-R (CR) and Capture-R Ready-Screen (RS), were compared to determine their acceptability for use in prenatal antibody screening. Ninety-six serum samples, screened using a saline antiglobulin test, were coded and tested by CR and RS at two laboratory sites using a blinded study design. Thirty of the samples were free of antibody, and 66 samples contained antibody. Parallel testing was also performed in both laboratories on 648 prenatal samples. The sensitivity and specificity of CR, based on the 96 previously screened samples, was 95 percent and 90 percent, respectively, and the sensitivity and specificity of RS was 90 percent and 89 percent, respectively. Antibodies detected only by CR included anti-K(1), -Ch(2), -Jka(1), -Lea(1), -Fya(1), -Mca(1), and -e(1). Antibodies detected only by RS included anti-Jka(5) and -E(1). The sensitivity and specificity of CR for the 648 prenatal samples was 100 percent for each, while the sensitivity and specificity of RS was 97 percent and 100 percent, respectively. Both CR and RS are acceptable techniques for prenatal antibody screening.

Basic statistics for clinicians: 1. Hypothesis testing

In the first of a series of four articles the authors explain the statistical concepts of hypothesis testing and p values. In many clinical trials investigators test a null hypothesis that there is no difference between a new treatment and a placebo or between two treatments. The result of a single experiment will almost always show some difference between the experimental and the control groups. Is the difference due to chance, or is it large enough to reject the null hypothesis and conclude that there is a true difference in treatment effects? Statistical tests yield a p value: the probability that the experiment would show a difference as great or greater than that observed if the null hypothesis were true. By convention, p values of less than 0.05 are considered statistically significant, and investigators conclude that there is a real difference. However, the smaller the sample size, the greater the chance of erroneously concluding that the experimental treatment does not differ from the control--in statistical terms, the power of the test may be inadequate. Tests of several outcomes from one set of data may lead to an erroneous conclusion that an outcome is significant if the joint probability of the outcomes is not taken into account. Hypothesis testing has limitations, which will be discussed in the next article in the series.

An index of scientific quality for health reports in the lay press

Although the quality of health reporting has been criticized for being unscientific, evaluations of health care reporting have been limited by the lack of a reliable and credible measure of scientific quality. We developed an index of scientific quality (ISQ) for health-related news reports and tested its reliability and sensibility. Items were generated from a survey of the literature and experts in research methodology. Items that were unclear, confusing or discriminated poorly between articles of high and low scientific quality were revised or deleted in an iterative process wherein potential criteria were independently applied to samples of 5 to 15 articles by 6 raters. To test the reliability of the final criteria 60 articles were drawn from three sampling frames: newspapers, magazines, and professional journals. Articles were intentionally selected to obtain a wide range of quality and topics. Two categories of raters were used: research assistants and physicians with research training. All 6 raters assessed all 60 articles. The sensibility of the index was tested by a questionnaire with 13 items related to face validity and content validity as well as other aspects of sensibility. The questionnaire was completed by 20 researchers and 13 health and science writers. The final ISQ includes 7 items that address the extent to which a report allows readers to draw conclusions about the applicability, validity and practical importance of the information that is reported. Chance corrected agreement (kappa) among all 6 raters for overall scientific quality was 0.62 (SE 0.02). The index was found to be sensible with only one major problem, the need for judgment in making ratings. While some degree of subjectivity appears to be inevitable in rating the scientific quality of health reports, the ISQ is acceptable reliable and credible and should be useful for evaluating and improving the scientific quality of health reporting.

HLA-restricted responses to M and N determinants in the primed lymphocyte test

We have studied the role of MNSs determinants in the primed lymphocyte test (PLT). The data demonstrate that incompatibility associated with the M or N antigens causes HLA-restricted proliferative responses in PLT. Responses to the M or N determinants required the presence of the same HLA-A antigen(s) on both the stimulator and the responder cells. No effects of S or s incompatibility were observed in this test. This is the first report of lymphocyte proliferative responses to "minor" alloantigens that require corecognition of the MHC determinants. These observations suggest possible new biological functions of these blood group antigens.

Transient Donath-Landsteiner haemolytic anaemia

Five children with 'paroxysmal cold haemoglobinuria' are described. In all of them an upper respiratory tract infection preceded the episode of acute intravascular haemolysis and potentially pathogenic organisms were recovered from four. The haematological features are presented and the importance of technique in the detection of the pathognomonic antibody is stressed and discussed in detail. Although the clinical manifestations are usually self-limiting and of short duration, it may be necessary, because of the rapidity and severity of anaemia, to provide interim support with appropriate blood transfusion. Since the disease is not usually recurrent and not clearly related to exposure to cold, it is suggested that it be re-named Donath-Landsteiner haemolytic anaemia.