Prevalence of Protein C Deficiency in the Healthy Population

Reported prevalence rates for protein C (PC) deficiency in the population at large have varied widely. The differences presumably reflect the existence of an apparently high number of clinically recessive forms of the deficiency. In an attempt to document more precisely the prevalence of PC deficiency in the healthy population we have measured PC activity in just under 10,000 blood donors in the West of Scotland. After repeat testing of donors with low results and then further observation and selection, 32 donors were identified who had individual mean PC activities below the age- and gender-specific study reference range. Assessment of available first degree relatives, and also PC gene analysis in 23 of these donors, allowed identification of at least 14 with an inheritable deficiency (8 by both family study and gene analysis, 3 by family study alone and 3 by gene analysis alone). Two recurring and seven unique point mutations, only one of which has been previously described, were identified. The observed prevalence of inherited PC deficiency was 1.45 per 1000 (95% Cl, 0.79/1000 to 2.43/1000). However after correcting for the possibility of missing some genuine inherited deficiencies we estimated the prevalence to be as high as 1 in 500. All cases of hereditary deficiency were asymptomatic with regard to thrombosis and none had a strong family history of thrombosis. These findings confirm the rather frequent occurrence of asymptomatic individuals with PC deficiency and support the hypothesis that additional defects in the anticoagulant pathways may be required to confer a high-thrombotic-risk phenotype.

Risk Factors for Pregnancy Associated Venous Thromboembolism

In an attempt to reduce the incidence of pregnancy associated venous thromboembolism (PA-VTE), some researchers have advocated screening of all women for the factor VLeiden mutation during early pregnancy. We have conducted a large retrospective study (over 72,000 deliveries) to determine if this would be useful. Sixty-two objectively confirmed venous thrombotic events (51 DVT, 11 PE) were recorded at two maternity units in the UK. The incidence of DVT was 0.71 per 1000 deliveries (95% CI 0.5-0.9) with 0.50 occurring in the antenatal period (95% CI 0.34-0.66) and 0.21 in the puerperium (95% CI 0.11-0.31). The incidence of PE was 0.15 per 1000 deliveries (95% CI 0.06-0.24), 0.07 antenatal (95% CI 0.01-0.13) and 0.08 in the puerperium (95% CI 0.02-0.14). Of these 62,50 attended for follow-up and thrombophilia screening. 28% of all episodes of PA-VTE had no CIinical risk factor for thrombosis or an identifiable thrombophilic abnormality. Deficiency of antithrombin was identified in 12% of individuals (95% CI 3-21) and the factor VLeiden mutation in 8% (95% CI 0.5-15.5). Based on estimates of the prevalence of the factor VLeiden mutation in the population, we estimate that the thrombotic risk for a woman during pregnancy or the puerperium with the defect is approximately 1 in 400-500. This figure would not lend support to the idea of random screening for the mutation in early pregnancy.

Isolated Familial Plasminogen Deficiency May not Be a Risk Factor for Thrombosis

Despite many reports of individuals with congenital plasminogen deficiency and thrombosis, there is still uncertainty whether heterozygous deficiency represents a real thrombophilic risk factor or simply a coincidental finding. We have addressed this issue by testing for plasminogen deficiency in a cohort of 9611 blood donors. Out of 66 donors with reduced plasminogen activity on two occasions 28 were shown to have a familial deficiency state (including 3 with dysplasminogen-aemia). Our observed prevalence rate for familial plasminogen deficiency, calculated at 2.9/1000 (95% Cl = 1.9-4.2 per 1000), was not significantly different from that calculated from published reports of congenital plasminogen deficiency in thrombotic cohorts (5.4/1000). Furthermore, with only two exceptions, all 80 donors and relatives with familial deficiency were asymptomatic with regard to thrombosis -including a 29 year old donor with suspected compound heterozygous hypoplasminogenaemia. These findings add further weight to the argument that familial heterozygous plasminogen deficiency, at least in isolation, does not constitute a significant thrombotic risk factor. However, it remains uncertain whether plasminogen deficiency, when combined with other thrombophilic conditions, may become more clinically important.

Plasminogen Levels in Healthy Volunteers -Influence of Age, Sex, Smoking and Oral Contraceptives

There is considerable doubt as to the importance of reduced plasminogen (PLG) activity as a risk factor for venous thrombosis. In the present study we have identified a wide range of PLG activities (25–200%) in a cohort of 9,611 blood donors. Males and females not taking hormonal contraceptives show a similar distribution of PLG, however, variation related to age appears to follow a different pattern in males and females. These differences are of doubtful clinical importance as are differences related to smoking. In contrast, females taking hormonal contraceptives or hormone replacement therapy (HRT) have up to 25% higher mean PLG levels in younger females but a less marked elevation (10%) is seen in 40–50 year olds. A PLG activity <65% was recorded in 61 donors, none of whom appeared to have a history of thrombosis. These findings do not support the notion that reduced PLG is an important thrombophilic risk factor, however, further investigation of the donors with low PLG is required.

Protein C Activity in Healthy Volunteers - Influence of Age, Sex, Smoking and Oral Contraceptives

Interpretation of protein C (PC) levels in a given individual has several limitations. A normal PC activity does not necessarily exclude a genetic deficiency nor can a reduced level confirm it. Measuring PC amidolytic activity in 9,648 healthy blood donors has allowed identification of demographic factors which cause variation in PC activity and further hinder interpretation. PC activity displays a log normal distribution and significant variation with age. This is most marked in young adult males when mean PC activity rises from 0.86 iu/ml (15–19 years) to 1.04 iu/ml (45–49 years; P <0.0001). Pre-menopausal females, who for most age ranges, have mean PC activity below their male contemporaries, show a less marked rise with age until the menopause when PC activity rises further. The use of hormonal contraceptive preparations is associated with an increase in mean PC activity of 0.05–0.08 iu/ml while smoking habit has no influence on PC activity.

In view of these findings we strongly recommend the use of age and sex restricted reference ranges when interpreting PC activity.

Antithrombin Cambridge II (Ala384Ser): Clinical, Functional and Haplotype Analysis of 18 Families

Thirty-one individuals from 18 unrelated families with antithrombin deficiency have been identified as having a single point mutation within codon 384 (13268 GCA→TCA) resulting in an alanine to serine substitution. Six families (11 individuals) were identified by the screening of individuals with thromboembolic disease or with a family history of thromboembolic disease, whilst the remaining 12 families (20 individuals) were identified by screening of asymptomatic blood donors. Four individuals had a history of venous thrombotic disease, a further 2 gave a history of superficial thrombophlebitis but the remaining 25 individuals were asymptomatic. Affected individuals demonstrated normal immunological levels of antithrombin but a decrease in anti-IIa activity in the presence of heparin. Haplotype analysis was used to examine the possibility of a founder effect to explain the high frequency of this non-CpG mutation. 29/31 individuals showed a single common “core” haplotype, the only variation existing in the number of copies of an (ATT)n repeat polymorphism – 13, 14, 15 or 17. The results suggest that at most there are four independent origins for this mutation.

Superficial Vein Thrombosis: Incidence in Association with Pregnancy and Prevalence of Thrombophilic Defects

Superficial venous thrombotic (SVT) events are a feature of thrombophilic abnormalities, particularly those involving the protein C pathway. We have determined the incidence of SVT associated with pregnancy and the early postpartum period in a retrospective study involving 72 000 deliveries. Fourty-nine cases occurring in 47 individuals were recorded, with an overall incidence of 0.68/1000 deliveries (95% CI 0.48-0.88). None had a previous history of deep vein thrombosis or pulmonary embolism. Most events occurred in the early post-partum period (0.54/1000 deliveries). Twenty-four/fourty-seven were screened for established thrombophilic abnormalities, with only 1 abnormality detected (FVLeiden heterozygote). Thrombophilia may play a minor role in the aetiology of SVT associated with pregnancy, although a larger study is required to confirm this.

Are Atrial Fibrillation Guidelines Altering Management? A Community Based Study

Background and Aims: We wanted to determine the prevalence of atrial fibrillation (AF) in a community based cross sectional study in greater Glasgow and how current anti thrombotic management compares to published guidelines. Methods: 1466 patients with AF were identified in General Practices in our community and 1008 consented to take part. Their demographic details and medical history were recorded. Results: 1466 patients (mean age 73.4; 55% female) with AF were identified, in our community, giving a prevalence of 1%. 53% of patients were on warfarin therapy. Of those not receiving warfarin, only one third had a putative contra-indication. The proportion of AF patients on warfarin increased with increasing stroke risk, and over the period of the study. Conclusions: Prevalence of AF was in keeping with previous estimates. The proportion of patients with AF receiving warfarin therapy appears to be increasing. In the moderate risk group, there was a tendency to use more warfarin in the younger age groups compared to the elderly. It was in the moderate and low risk groups that there was still evidence of deviation from published guidelines.

Sex difference in the risk of recurrent venous thrombosis: a detailed analysis in four European cohorts

BACKGROUND

Previous analyses reported a higher risk of recurrent venous thrombosis in men than women.

OBJECTIVES

We aimed to assess the risk of recurrence in men compared with women whilst taking female reproductive risk factors (oral contraception, postmenopausal hormone therapy and pregnancy) into account. In addition, we hypothesized that the sex difference in venous thrombosis was related to F9 Malmö, an X-linked prothrombotic factor.

METHODS

In four pooled European cohorts (CARROT study, Glasgow, UK; CVTE study, Cambridge, UK; AUREC study, Vienna, Austria; and LETS follow-up study, Leiden, the Netherlands), the risk of recurrent venous thrombosis was calculated in men, women with reproductive risk factors and women without reproductive risk factors at the time of their first venous thrombosis. F9 Malmö was genotyped and carriers and non-carriers contrasted.

RESULTS

In total, 2185 patients with a first venous thrombosis, 1043 men and 1142 women, were included. Overall, men had a 2.8-fold (95% confidence interval [CI], 2.2-3.4) higher risk of recurrent venous thrombosis than women. This risk was 5.2-fold (95% CI, 3.5-7.7) higher in men than in women with reproductive risk factors, and 2.3-fold (95% CI, 1.7-3.2) higher in men than in women without reproductive risk factors. No difference in risk of recurrence was found for carriers vs. non-carriers of F9 Malmö.

CONCLUSION

Men experienced a recurrent venous thrombosis twice as often as women without reproductive risk factors. These findings indicate that men have a higher intrinsic risk of venous thrombosis than women, which is partly masked by female reproductive risk factors. The sex difference cannot be explained by F9 Malmö.

Risk of recurrence after a first unprovoked venous thromboembolism: external validation of the Vienna Prediction Model with pooled individual patient data

BACKGROUND

In order to stratify patients with a first unprovoked venous thromboembolism (VTE) according to their recurrence risk and to identify those who would actually benefit from indefinite anticoagulation, three prediction models have been developed so far; none of them has been yet externally validated.

OBJECTIVE

To externally validate the Vienna Prediction Model (VPM), a prediction guide for estimating the recurrence risk after a first unprovoked VTE developed through Cox modeling and including sex, D-dimer and index VTE site as predictors.

PATIENTS/METHODS

Nine hundred and four patients pooled from five prospective studies evaluating the prognostic value of D-dimer for VTE recurrence served as the validation cohort. The validity of the VPM in stratifying patients according to their relative recurrence risk (discrimination) and in predicting the absolute recurrence risk (calibration) was tested with survival analysis methods.

RESULTS

The ability of the VPM to distinguish patients' risk for recurrent VTE in the validation cohort was at least as good as in the original cohort, with a calibration slope of 1.17 (95% confidence interval 0.71-1.64; P = 0.456 for the hypothesis of a significant difference from 1), and a c-statistic of 0.626 (vs. 0.651 in the original derivation cohort). The VPM absolute predictions in terms of cumulative rates tended to underestimate the observed recurrence rates at 12 months.

CONCLUSIONS

By using a pooled individual patient database as a validation cohort, we confirmed the ability of the VPM to stratify patients with a first unprovoked VTE according to their risk of recurrence.

Predicting disease recurrence in patients with previous unprovoked venous thromboembolism: a proposed prediction score (DASH)

BACKGROUND

In patients with unprovoked venous thromboembolism (VTE), the optimal duration of anticoagulation is anchored on estimating the risk of disease recurrence.

OBJECTIVES

We aimed to develop a score that could predict the recurrence risk following a first episode of unprovoked VTE, pooling individual patient data from seven prospective studies.

METHODS

One thousand eight hundred and eighteen cases with unprovoked VTE treated for at least 3 months with a vitamin K antagonist were available for analysis. Optimism-corrected Cox regression coefficients were used to develop a recurrence score that was subsequently internally validated by bootstrap analysis.

RESULTS

Abnormal D-dimer after stopping anticoagulation, age <50 years, male sex and VTE not associated with hormonal therapy (in women) were the main predictors of recurrence and were used to derive a prognostic recurrence score (DASH, D-dimer, Age, Sex, Hormonal therapy) showing a satisfactory predictive capability (ROC area =0.71). The annualized recurrence risk was 3.1% (95% confidence interval [CI], 2.3-3.9) for a score ≤ 1, 6.4% (95% CI, 4.8-7.9) for a score=2 and 12.3% (95% CI, 9.9-14.7) for a score ≥ 3. By considering at low recurrence risk those patients with a score ≤ 1, life-long anticoagulation might be avoided in about half of patients with unprovoked VTE.

CONCLUSIONS

The DASH prediction rule appears to predict recurrence risk in patients with a first unprovoked VTE and may be useful to decide whether anticoagulant therapy should be continued indefinitely or stopped after an initial treatment period of at least 3 months.

Does the clinical presentation and extent of venous thrombosis predict likelihood and type of recurrence? A patient-level meta-analysis

AIM

To determine if the mode of presentation of venous thromboembolism (VTE), as deep vein thrombosis (DVT) or pulmonary embolism (PE), predicts the likelihood and type of recurrence.

METHODS

We carried out a patient-level meta-analysis of seven prospective studies in patients with a first VTE who were followed after anticoagulation was stopped. We used Kaplan-Meier analysis to determine the cumulative incidence of recurrent VTE according to mode of presentation, and multivariable Cox regression to calculate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for mode of and extent of DVT as potential risk factors for recurrence.

RESULTS

The 5-year cumulative rate of recurrent VTE in 2554 patients was 22.6%. In 869 (36.1%) patients with PE, the 5-year rate of any recurrence (DVT or PE) was 22.0%, and recurrence as PE was 10.6%. In 1365 patients with proximal DVT, the 5-year recurrence rate was 26.4%, and recurrence with PE was 3.6%. The risk of recurrence as PE was 3.1-fold greater in patients presenting with symptomatic PE than in patients with proximal DVT (HR, 3.1; 95% CI, 1.9-5.1). Patients with proximal DVT had a 4.8-fold higher cumulative recurrence rate than those with distal DVT (HR, 4.8; 95% CI, 2.1-11.0).

CONCLUSION

Whilst DVT and PE are manifestations of the same disease, the phenotypic expression is predetermined. Patients presenting with PE are three times more likely to suffer recurrence as PE than patients presenting with DVT. Patients presenting with calf DVT are at low risk of recurrence and at low risk of recurrence as PE.

Vitamin B12 deficiency following restorative proctocolectomy

OBJECTIVE

Restorative proctocolectomy (RP) involves terminal ileal resection and formation of a small bowel reservoir that predisposes to bacterial overgrowth. It was anticipated that these patients would be at risk of vitamin B12 deficiency.

METHOD

Vitamin B12 levels were measured sequentially in 171 patients who underwent RP. Prospective results were obtained from all 20 patients undergoing pouch formation after the commencement of the study. Further results were obtained retrospectively from case notes and computerized laboratory records of the 151 patients who underwent RP prior to the commencement of the study and these were correlated with the results of follow-up samples taken prospectively from the same patients after the commencement of the study. The median age of the patients was 40 years (range: 13-67) and the median duration of follow up was 5.4 years (range: 1-12). Patients with an abnormally low serum B12 level underwent both a Schilling and a hydrogen breath test. Eight of these patients were then treated with oral vitamin B12.

RESULTS

Abnormally low serum B12 levels were found in 25% of patients. Forty per cent of our patient group had three or more sequential B12 measurements and of these, 66% showed steadily declining B12 levels. Ninety-four per cent of patients with low B12 had a normal Schilling test and were negative for bacterial overgrowth.

CONCLUSION

Subnormal vitamin B12 levels develop in almost one-quarter of patients after pouch surgery. The exact mechanism for B12 deficiency in these patients is uncertain. In the majority of patients undergoing RP, vitamin B12 levels fall on sequential measurement. Serum B12 levels should be measured during follow up and pouch patients with subnormal B12 levels, should see them successfully restored to a normal value after treatment with oral B12 replacement therapy.

Dementia in subjects with atrial fibrillation: hemostatic function and the role of anticoagulation

BACKGROUND

Atrial fibrillation (AF) is associated with cognitive impairment and dementia, perhaps through encouraging a prothrombotic state and cardioembolism.

OBJECTIVES

We wished to test the hypotheses that hemostatic function is altered in subjects with AF who develop dementia, and that long-term warfarin anticoagulation is protective against this complication.

PATIENTS AND METHODS

Recruitment was from an observational cohort study of AF. Baseline assessment included measurement of plasma fibrinogen, fibrin D-dimer, prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complexes (TAT), von Willebrand factor and tissue plasminogen activator. We assessed cognitive function after 3 years' follow-up using the 13-item modified Telephone Interview for Cognitive Status (TICSm) and the short form of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE).

RESULTS

Of the 218 subjects assessed, 145 (66%) were prescribed warfarin. Forty-nine (22%) met TICSm/IQCODE criteria for dementia. D-dimer, F1+2 and TAT levels were higher in AF subjects with dementia compared with those without (medians 81 vs. 60 ng mL(-1), P = 0.008; 0.76 vs. 0.49 nmol L(-1), P = 0.006; and 1.78 vs. 1.44 microg L(-1), P = 0.003, respectively). These associations became of borderline statistical significance following adjustment for age. Logistic regression showed a trend towards warfarin use being independently associated with reduced prevalence of dementia (odds ratio 0.52, P = 0.08).

CONCLUSIONS

We found evidence of increased thrombin generation and fibrin turnover in subjects with AF and dementia compared with those without dementia. Long-term warfarin use may be protective against the development of dementia in subjects with AF.

Immediate haemostasis with recombinant factor VIIa for haemorrhage following Hickman line insertion in acute myeloid leukaemia

Bleeding following Hickman line insertion is not uncommon but can be life threatening, especially in the presence of coagulopathy and thrombocytopenia following chemotherapy. Treatment to control the bleeding can be challenging and treatment options are limited. We present our experience of a patient who had persisting haemorrhage immediately following Hickman line insertion for administration of chemotherapy for relapsed acute myeloid leukaemia. Haemostasis could not be achieved after FFP and platelet administration. A single dose of recombinant factor VIIa (rhFVIIa) stopped the bleeding immediately, avoiding the need for surgical intervention or line removal. Our experience indicates rhFVIIa may be an effective option for bleeding related to Hickman line insertion.

'Last-ditch' use of recombinant factor VIIa in patients with massive haemorrhage is ineffective

BACKGROUND AND OBJECTIVES

The aim of this retrospective study was to assess the effect of activated recombinant factor VII (rFVIIa) on the natural history of massive transfusion episodes.

MATERIALS AND METHODS

During 2002, outcome parameters were assessed in 50 patients transfused with more than 10 units of packed red cells. The effect of the addition of rFVIIa in 10 patients, with intractable bleeding, was then observed.

RESULTS

Overall mortality was 20% at 24 h and 34% at 7 days. Severe coagulopathy was confirmed as a serious negative prognostic factor and occurred in 42% of patients overall, but in 70% of rFVIIa-treated patients. Transient cessation or reduction of bleeding was noted in 60% of patients following rFVIIa infusion. However, 24-h and 7-day mortality rates were 40% and 70%, respectively, in this group.

CONCLUSIONS

Last-ditch rFVIIa therapy in patients resistant to conventional treatment did not rescue these patients or significantly alter outcomes.

Interaction between hormone replacement therapy preparations and oral anticoagulant therapy

There is limited information regarding the interaction of hormone replacement therapy (HRT) and oral anticoagulants. Following the acute over-anticoagulation of two women shortly after the initiation of tibolone, we have undertaken a retrospective review of anticoagulated women to determine if the dose of oral anticoagulants and quality of anticoagulant control are affected by the introduction of HRT. We demonstrate that acute over-anticoagulation consistently occurs following the commencement of tibolone and requires anticoagulant dose modification to re-establish target international normalised ratio (INR). In contrast, non-tibolone HRT preparations do not consistently alter anticoagulant control or dose requirements.

The application of molecular biology

Molecular biology methods have tremendous value not only in the investigation of basic scientific questions, but also in application to a wide variety of problems affecting the overall human condition. Disease prevention and treatment, generation of new protein products, and manipulation of plants and animals for desired phenotypic traits are all applications that are routinely addressed by the application of molecular biology methods. Because of the wide applicability of these methods, they are rapidly becoming a pervasive--some would argue invasive--aspect of our technologically based society. The public concerns that address the application of these methods should be addressed by informed public discussion and debate. While scientists can be extremely critical of the quality, interpretation, and significance of experimental results, they have a rather remarkable tendency to be non-judgmental of the relative social merits of many applications of scientific research. It remains a public responsibility to be sufficiently well-informed to critically assess the merits of applied science research and participate in a communal decision-making process regarding the extent to which a new technology will be allowed to affect society.

Platelet and cardiac function in Darier's disease

ATP2A2, the gene that is abnormal in Darier's disease, encodes SERCA2, a calcium pump that is expressed in many tissues. The wide expression of SERCA2 might suggest that ATP2A2 mutations would cause a multisystem disease. There is however, no evidence of consistent extracutaneous manifestations of Darier's disease. We have conducted preliminary studies in patients with Darier's disease, in two extracutaneous systems in which SERCA2 is known to be important, in order to investigate whether subtle defects have been overlooked. We found no evidence for altered cardiac function in 10 patients using two-dimensional, colour and Doppler echocardiography. There were no consistent defects in platelet function in 12 patients, using bleeding time and aggregation studies. We conclude that the skin is sensitive to defects in SERCA2 function to which other systems appear robust.

Oral anticoagulation and hemorrhagic complications in an elderly population with atrial fibrillation

BACKGROUND

Warfarin sodium therapy in patients with atrial fibrillation markedly reduces the incidence of embolic stroke. However, in elderly patients warfarin therapy is often underused owing to the perceived higher risk of hemorrhagic complications.

OBJECTIVES

To assess the quality of anticoagulant control and the incidence of hemorrhagic complications and stroke in an elderly population (>75 years old) compared with a younger control group (between 60 and 69 years) and to assess the quality of anticoagulant control and incidence of hemorrhagic complications in those patients who recently commenced receiving warfarin therapy (first year of therapy).

PATIENTS AND METHODS

In this retrospective follow-up study, anticoagulant control and the incidence of hemorrhagic complications and stroke were assessed in an elderly population (>75 years old) compared with a younger control group (between 60 and 69 years), all with atrial fibrillation(target international normalized ratio [INR] 2.5) and attending a hospital outpatient anticoagulant clinic.

RESULTS

A total of 328 patients were studied over a 21-month period. There were 204 patients in the control group providing 288 patient-years of follow-up and 124 patients in the elderly group providing 170 patient-years of follow-up. The percentage of INR results in the target range was not statistically significantly different between the elderly and control groups (71.5% vs 66.1%) and the occurrences of incidences of INR greater than 7 were 4.2% in the control group and 4.7% in the elderly group (P =.96). The incidences of major hemorrhage were 2.8% per year in the elderly group and 2.9% per year in the control group (P =.96); overall incidence was 2.8% (95% confidence interval, 1.3%-4.4%). One hundred one of the 328 patients studied commenced warfarin therapy during or within 3 months of the start of the study. In this induction group, 62.1% of INRs were within the target range compared with 70.9% of INRs in patients who had been receiving warfarin therapy for more than 3 months at the start of the study (P =.002). The incidences of INR greater than 7 and major hemorrhage were 7.9% per year and 6.9% per year, respectively, in the cohort who recently began warfarin therapy compared with 3.4% per year and 1.7% per year in the group who were receiving warfarin therapy for more than 3 months.

CONCLUSION

While it was impossible to consider any selection bias at the level of referral to the clinic, these findings suggest that the elderly population attending our anticoagulant clinic did not have poorer anticoagulant control or an increased incidence of hemorrhage while receiving warfarin therapy.

A study of Protein S antigen levels in 3788 healthy volunteers: influence of age, sex and hormone use, and estimate for prevalence of deficiency state

Total Protein S (tPS) and free Protein S (fPS) antigen levels were measured in 3788 healthy blood donors. Men had higher levels of both parameters than women (P < 0.001). Age had no effect on tPS in men, although there was a slight reduction in fPS levels with increasing age. In women increasing age was associated with a significant increase in tPS levels (P < 0.001) but had no effect on fPS after adjustment for menopausal state. Oral contraceptive pill (OCP) use significantly lowered tPS but had no effect on fPS. In post-menopausal women, hormone replacement therapy (HRT) use had no statistically significant effect on either tPS or fPS. Donors with tPS or fPS levels in the lowest percentile (n = 56) were retested; only nine with repeat low levels were identified, eight of whom had persistently low levels over a 4-7-year follow-up. Acquired deficiency was excluded. When possible, family studies were performed, leading to an estimate of prevalence of familial PS deficiency of between 0.03% and 0.13% in the general population.

Pain assessment in cognitively impaired and unimpaired older adults: a comparison of four scales

The purpose of the study was to compare the psychometric properties of four established pain scales in a population of hospitalized older adults (mean age, 76 years) with varying levels of cognitive impairment. Patients made ratings of current pain three times/day for 7 days. They also made retrospective daily, weekly, and bi-weekly ratings of usual, worst, and least pain levels over a 14-day period. Ratings were made on four different scales, varying in numeric and verbal demands: a five-point verbal rating scale, a seven-point faces pain scale, a horizontal 21-point (0-100) box scale, and two vertical 21-point (0-20) box scales (measuring pain intensity and pain unpleasantness). The accuracy, reliability, construct validity, postdictive validity, and bias susceptibility of each scale were evaluated. The horizontal 21-point box scale emerged as the best scale with respect to both psychometrics and validity, regardless of mental status. Pain intensity did not vary as a function of mental status. Retrospective estimates of pain varied by mental status: a combination of usual/worst pain was best for cognitively impaired patients, while a combination of usual/least pain was best for unimpaired patients. These findings support the use of the 21-point box scale for pain assessment in older patients, including those with mild-to-moderate cognitive impairment. They also support the ability of older, cognitively impaired patients to rate pain reliably and validly.

Work injury management of refractory low back pain: relations with ethnicity, legal representation and diagnosis

While psychosocial factors are known to influence treatment outcomes in low back pain patients, relatively little is known about how they may influence work injury management of low back pain. This study examined medical and psychosocial factors associated with work injury management decisions relative to patients with occupational low back pain. A retrospective review of 132 patients who had settled their injury claims showed that two psychosocial factors, ethnicity and litigation status, were associated with work injury management. Temporary total disability costs and impairment ratings were lower for African Americans than for Caucasians, but only in the absence of legal representation. Similarly, patients with specific pathology underwent more treatment, especially diagnostic testing, than patients with non-specific back pain, but only in the presence of legal representation. Having evidence of a specific lesion and legal representation were also associated with claimants' final disability ratings. Results are discussed in terms of a model of social judgment in which properties of the judge, target, and context influence judgments. Implications for work injury management and disability determination, as well as future research are discussed.

Combined prednisolone and intravenous immunoglobulin treatment for acquired factor VIII inhibitors: a 2-year review

Acquired inhibitors to factor VIII (FVIII) are rare, but life-threatening in up to 22% of cases. The optimal therapy for suppression of these inhibitors remains unclear. Prednisolone is the mainstay of therapy, producing responses in approximately 30% of cases. Intravenous immunoglobulin (IVIg) has a similar response rate, but a more rapid effect. We report the results of prednisolone 1 mg kg(-1) combined with IVIg 2 g kg(-1) in divided doses as first-line therapy in seven consecutive patients with acquired FVIII inhibitors. All patients were bleeding at the time of diagnosis with prolonged activated partial thromboplastin time. There were four complete responses, one partial response, one nonresponse and one with an inadequate follow-up for assessment of response, giving an overall response rate of 71%. In all complete responders the inhibitor declined rapidly and was undetectable by day 21 from start of treatment. Therapy was well tolerated and responses have been maintained off treatment for 2-8 months. This is a safe, well-tolerated rapidly acting regimen with good response rates.

Injecting drug use is a risk factor for deep vein thrombosis in women in Glasgow

Three hundred and twenty-two consecutive women aged 16-70 years who presented with objectively confirmed symptomatic venous thromboembolism (VTE) were studied to determine precipitating factors for thrombosis. One hundred and eighty-seven presented with deep vein thrombosis (DVT), 116 with either definite or possible pulmonary embolism (PE) and 19 with both DVT and PE. Injecting drug use (IDU) via femoral vein puncture was a common risk factor for DVT, associated with 21.4% of all cases of DVT and 52.4% of cases of DVT in women under 40 years. All women with drug-related thrombosis presented with DVT. None presented with symptomatic PE. A number of clinically diagnosed DVT associated with IDU were also documented, suggesting that IDU may be the most common risk factor for DVT in our region. DVT associated with IDU presents significant management challenges.

Assessing pain in older adults

In recent years, pain control has become a topic of increased interest in the United States. Although the interest originated in professional societies (the American Pain Society has called for pain to be treated as a “fifth vital sign”), regulatory agencies have now picked up on the issue. For example, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO), probably the most important of the regulatory agencies, has established standards for pain assessment to be implemented by the upcoming year (JCAHO, 2000).

Disability management of low back injuries by employer-retained physicians: ratings and costs

BACKGROUND

Medico-legal models of disability determination for low back pain lack empirical support. Besides diagnostic and functional parameters, social and situational factors may influence impairment/disability ratings and costs.

METHODS

Archival data from employer-retained occupational medicine physician files and public court records were examined for 184 Workers' Compensation claimants with low back injuries. Regression was used to predict ratings, costs, and settlement duration from medical, functional, social, and situational variables.

RESULTS

Diagnosis, surgery, pain, rating year, and clinic predicted impairment ratings from employer-retained physicians. The clinic effect partially reflected claimant ethnicity. Diagnosis, surgery, tests ordered, legal representation, and impairment rating predicted disability ratings at the administrative law judge level. Diagnosis, tests, and impairment rating predicted costs. For musculoskeletal diagnoses, settlement duration was related negatively to treatment duration and positively to costs.

CONCLUSIONS

Social and situational parameters influence disability management among employer-retained physicians, while functional variables have little impact. For musculoskeletal low back pain, increased disability and cost may result from variation in treatment duration.

Internist Judgments of Chronic Low Back Pain

OBJECTIVE

To examine the consistency of internist judgments about low back pain; to examine the influence of different clinical factors on those judgments.

DESIGN

2 x 4 mixed between- and within-subjects analog experiment.

SETTING

Academic health sciences center, school of medicine; department of internal medicine.

PARTICIPANTS

Forty-eight internal medicine physicians.

INTERVENTIONS

Vignettes describing hypothetical chronic low back pain patient varied by patient pain level (low versus high) and clinical information type (history versus physical examination versus functional disability versus medical diagnostics).

OUTCOME MEASURES

Clinical judgments regarding patient medical, psychological, and disability status; referral, treatment, and test ordering options.

RESULTS

Within-physician consistency was very high, while between-physician consistency was very low. Medical diagnostics had the only consistent influence on judgments. Patient pain level had no effect. Physical examination and functional information had little or no effect.

CONCLUSIONS

While there is little agreement among internists regarding judgments of low back pain, individual physicians hold consistently to their opinions. These findings suggest that management of low back pain may be idiosyncratic, potentially compromising patient care.

Introductory experiments in recombinant DNA

Nine practical exercises demonstrate the basic principles in recombinant DNA. The exercises explain the principles that DNA equals genes and that changes in DNA cause changes in genetic properties. The aim is to provide a teaching resource that can be used to illustrate the theory and applications of molecular biology to highschool students, undergraduate students, medics, dentists, doctors, nurses, life scientists, and anyone learning the basics of DNA technology.

A prospective randomized study to determine the optimal dose of intravenous vitamin K in reversal of over-warfarinization

The optimal management of asymptomatic overanticoagulated patients remains unknown. We measured international normalized ratio (INR), activated partial thromboplastin time (APTT) and prothrombin fragment 1 + 2 (F1 + 2) over 7 d in 24 asymptomatic or mildly haemorrhagic patients on warfarin with prolonged INR of > 7.0 who were randomized to receive 0.5 mg, 1 mg or 2 mg intravenous vitamin K. Of six severely overanticoagulated patients (INR > 9.5 with APTT ratio > 2), five failed to achieve an INR < or = 4.0 on day 1, irrespective of vitamin K dose given. In the remaining 18 cases, an optimal response (INR 2-4 at day 1) was observed in 67% of those receiving 0.5 mg vitamin K, but only in 33% of those receiving 1 or 2 mg, the majority of whom developed an INR < 2.0. Our results support an optimal dose of 0.5 mg i.v. vitamin K for most overanticoagulated patients, with possibly a repeat dose in the small group of severely overanticoagulated patients.

Prothrombin 20210 G-->A, MTHFR C677T mutations in women with venous thromboembolism associated with pregnancy

Over 50 unselected women with maternal venous thromboembolism were screened for the prothrombin 20210 G-->A and MTHFR C677T mutations, in addition to screening for other thrombophilias. The prevalence of thrombophilia in these women was compared with its prevalence in the general population in our area. The prothrombin (OR 4.4; 95% CI 1.2-16) and factor V Leiden (OR 4.5; 95% CI 2.1-14.5) mutations were more common in our patients, compared with the general population, whereas women homozygous for the C677T mutation in the methylene tetrahydrofolate reductase gene (OR 0.45; 95% CI 0.13-1.58) were not. It is recommended that women with a personal or strong family history of venous thromboembolism should be screened for the prothrombin mutation either before or early in pregnancy, in addition to screening for other thrombophilias. Screening for the MTHFR mutation does not appear to identify women at increased risk of maternal venous thrombosis.

Lipoprotein (a), cholesterol and triglycerides in women with venous thromboembolism

Plasma concentrations of lipoprotein (a), total cholesterol, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol and triglyceride were measured in 62 women who had suffered an episode of objectively confirmed venous thromboembolism (VTE) at < or = 50 years of age, and in 98 age-matched female controls. The mean body mass index (BMI) of cases was significantly (P < 0.001) higher than that of controls. Plasma triglyceride was significantly higher, and total cholesterol/LDL- and HDL-cholesterol significantly lower, in cases compared with controls. After adjustment for BMI, the plasma total cholesterol and LDL-cholesterol remained significantly lower in cases. No significant differences in mean plasma lipoprotein (a) levels were identified between cases and controls. Lipoprotein (a) does not appear to be significantly associated with the development of VTE in young women. The increased risk of VTE in obese subjects may be mediated, at least in part, via hypertriglyceridaemia, which has previously been demonstrated to have effects on levels of coagulation factors, natural anticoagulants, and plasminogen activator inhibitor type 1.

Prevalence of the post-thrombotic syndrome in young women with previous venous thromboembolism

The prevalence of mild, moderate and severe post-thrombotic syndrome (PTS) among 43 young women with a previous single episode of deep vein thrombosis (DVT) was 67%, 7% and 0% respectively. Subjects were assessed at a mean 51 months after the event. Moderate PTS was more common in women with recurrent (n = 9) DVT (44%, P < 0.001). Chronic venous insufficiency, assessed by light reflection rheography (LRR), was significantly (P < 0.05) more prevalent in women with single previous DVT (n = 40), recurrent DVT (n = 9) and isolated pulmonary embolism (PE) (n = 19) compared with healthy age-matched controls (odds ratios 10.9, 52.4 and 3.8 respectively). LRR findings correlated with moderate, but not mild, PTS. There was no correlation between development of PTS and body mass index.

Stenotrophomonas maltophilia: an increasing problem in patients with acute leukaemia

Stenotrophomonas maltophilia (previously Pseudomonas maltophilia and Xanthomonas maltophilia) is an increasing problem as an opportunistic pathogen in immunocompromised patients such as those with acute leukaemia. Infection is difficult to treat and eradicate due to its inherent and quickly acquired resistance to many antibiotics. Presentation with unusual cutaneous lesions is not uncommon and can present diagnostic difficulties. We present two cases which highlight the classical features of this infection in leukaemic patients, and discuss the need for early antibiotic treatment with regimens including cotrimoxazole, and the consideration of prompt central venous catheter removal.

Restarting anticoagulation in prosthetic heart valve patients after intracranial haemorrhage: a 2-year follow-up

35 patients with oral anticoagulant (OAC) related intracranial or intraspinal haemorrhage were studied to determine treatment received, outcome and rate of recurrent bleeding and thromboembolism after restarting OAC. All patients underwent active anticoagulant reversal and in 14 patients with prosthetic heart valves (PHV) the INR remained below 2.0 for 0-19d (median 7) with no thromboembolic events. 10 patients received heparin, although a therapeutic level was rarely achieved. 13 patients with PHV were restarted on OAC and followed for a median 23.5 months. One patient had recurrent intracranial bleeding. 3/13 patients had cerebral embolic events despite anticoagulation. We conclude that in PHV patients temporary cessation of OAC is safe and the risk of recurrent bleeding after restarting OAC is low.