Effectiveness of terbutaline pump for the prevention of preterm birth. A systematic review and meta-analysis

BACKGROUND

Subcutaneous terbutaline (SQ terbutaline) infusion by pump is used in pregnant women as a prolonged (beyond 48-72 h) maintenance tocolytic following acute treatment of preterm contractions. The effectiveness and safety of this maintenance tocolysis have not been clearly established. We aimed to systematically evaluate the effectiveness and safety of subcutaneous (SQ) terbutaline infusion by pump for maintenance tocolysis.

METHODOLOGY/PRINCIPAL FINDINGS

MEDLINE, EMBASE, CINAHL, the Cochrane Library, the Centre for Reviews and Dissemination databases, post-marketing surveillance data and grey literature were searched up to April 2011 for relevant experimental and observational studies. Two randomized trials, one nonrandomized trial, and 11 observational studies met inclusion criteria. Non-comparative studies were considered only for pump-related harms. We excluded case-reports but sought FDA summaries of post-marketing surveillance data. Non-English records without an English abstract were excluded. Evidence of low strength from observational studies with risk of bias favored SQ terbutaline pump for the outcomes of delivery at <32 and <37 weeks, mean days of pregnancy prolongation, and neonatal death. Observational studies of medium to high risk of bias also demonstrated benefit for other surrogate outcomes, such as birthweight and neonatal intensive care unit (NICU) admission. Several cases of maternal deaths and maternal cardiovascular events have been reported in patients receiving terbutaline tocolysis.

CONCLUSIONS/SIGNIFICANCE

Although evidence suggests that pump therapy may be beneficial as maintenance tocolysis, our confidence in its validity and reproducibility is low, suggesting that its use should be limited to the research setting. Concerns regarding safety of therapy persist.

Pre-analytic and analytic sources of variations in thiopurine methyltransferase activity measurement in patients prescribed thiopurine-based drugs: A systematic review

OBJECTIVES

Low thiopurine S-methyltransferase (TPMT) enzyme activity is associated with increased thiopurine drug toxicity, particularly myelotoxicity. Pre-analytic and analytic variables for TPMT genotype and phenotype (enzyme activity) testing were reviewed.

DESIGN AND METHODS

A systematic literature review was performed, and diagnostic laboratories were surveyed.

RESULTS

Thirty-five studies reported relevant data for pre-analytic variables (patient age, gender, race, hematocrit, co-morbidity, co-administered drugs and specimen stability) and thirty-three for analytic variables (accuracy, reproducibility). TPMT is stable in blood when stored for up to 7 days at room temperature, and 3 months at -30°C. Pre-analytic patient variables do not affect TPMT activity. Fifteen drugs studied to date exerted no clinically significant effects in vivo. Enzymatic assay is the preferred technique. Radiochemical and HPLC techniques had intra- and inter-assay coefficients of variation (CVs) below 10%.

CONCLUSION

TPMT is a stable enzyme, and its assay is not affected by age, gender, race or co-morbidity.

Assessment of thiopurine S-methyltransferase activity in patients prescribed thiopurines: a systematic review

BACKGROUND

The evidence for testing thiopurine S-methyltransferase (TPMT) enzymatic activity or genotype before starting therapy with thiopurine-based drugs is unclear.

PURPOSE

To examine the sensitivity and specificity of TPMT genotyping for TPMT enzymatic activity, reducing harm from thiopurine by pretesting, and the association of thiopurine toxicity with TPMT status in adults and children with chronic inflammatory diseases.

DATA SOURCES

MEDLINE, EMBASE, the Cochrane Library, and Ovid HealthSTAR (from inception to December 2010) and BIOSIS and Genetics Abstracts (to May 2009).

STUDY SELECTION

Two reviewers screened records and identified relevant studies in English.

DATA EXTRACTION

Data on patient characteristics, outcomes, and risk for bias were extracted by one reviewer and independently identified by another.

DATA SYNTHESIS

54 observational studies and 1 randomized, controlled trial were included. Insufficient evidence addressed the effectiveness of pretesting. Genotyping sensitivity to identify patients with low and intermediate TPMT enzymatic activity ranged from 70.33% to 86.15% (lower-bound 95% CI, 54.52% to 70.88%; upper-bound CI, 78.50% to 96.33%). Sparse data precluded estimation of genotype sensitivity to identify patients with low to absent enzymatic activity. Genotyping specificity approached 100%. Compared with noncarriers, heterozygous and homozygous genotypes were both associated with leukopenia (odds ratios, 4.29 [CI, 2.67 to 6.89] and 20.84 [CI, 3.42 to 126.89], respectively). Compared with intermediate or normal activity, low TPMT enzymatic activity was significantly associated with myelotoxicity and leukopenia.

LIMITATION

Available evidence was not rigorous and was underpowered to detect a difference in outcomes.

CONCLUSION

Insufficient evidence addresses the effectiveness of TPMT pretesting in patients with chronic inflammatory diseases. Estimates of the sensitivity of genotyping are imprecise. Evidence confirms the known associations of leukopenia or myelotoxicity with reduced TPMT activity or variant genotype.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality.

Assessment of thiopurine methyltransferase activity in patients prescribed azathioprine or other thiopurine-based drugs

OBJECTIVES

To examine whether pretreatment determination of thiopurine methyltransferase (TPMT) enzymatic activity (phenotyping) or TPMT genotype, to guide thiopurine therapy in chronic autoimmune disease patients, reduces treatment harms. Other objectives included assessing: preanalytic, analytic, and postanalytic requirements for TPMT testing; diagnostic accuracy of TPMT genotyping versus phenotyping; association of thiopurine toxicity with TPMT genotypic or phenotypic status; and costs of testing, care, and treating drug-associated complications.

DATA SOURCES

MEDLINE®, EMBASE®, and Healthstar were searched from inception to May 2010; the Cochrane Library® to October 2009; and BIOSIS®, Genetics Abstracts, and EconLit™ to May 2009, for English language records.

REVIEW METHODS

A reviewer screened records, and a second reviewer verified exclusions and subsequent selection of relevant studies. Studies in patients with leukemia and organ transplant were excluded. Additionally, laboratories that provide TPMT analytical services were surveyed to assess means of TPMT testing in practice. Where possible, risk of bias was assessed using standard criteria. Meta-analyses estimated diagnostic sensitivity, and specificity; and odds ratios of associations.

RESULTS

1790 titles or abstracts, and 538 full text records were screened. 114 observational studies and one RCT were included. Majority of studies were rated fair quality, except for diagnostic studies with 37 percent of studies rated poor. In general, there were few patients who were homozygous (or compound heterozygous) for TPMT variant alleles in the included studies limiting applicability. There is insufficient evidence examining effectiveness of pretesting in terms of reduction in clinical adverse events. Sufficient preanalytical data were available regarding preferred specimen collection, stability and storage conditions for TPMT testing. There was no clinically significant effect of age, gender, various coadministered drugs, or most morbidities (with the exception of renal failure and dialysis). TPMT phenotyping methods had coefficients of variation generally below 10 percent. TPMT genotyping reproducibility is generally between 95-100 percent. The sensitivity of genotyping to identify patients with low or intermediate TPMT enzymatic activity is imprecise, ranging from 70.70 to 82.10 percent (95 percent CI, lower bound range 37.90 to 54.00 percent; upper bound range 84.60 to 96.90 percent). Sensitivity of homozygous TPMT genotype to correctly identify patients with low to absent enzymatic activity was 87.10 percent (95 percent CI 44.30 to 98.30 percent). Genotyping specificity approached 100 percent. Leukopenia was significantly associated with low and intermediate enzymatic activity (low activity OR 80.00, 95 percent CI 11.5 to 559; and intermediate activity OR 2.96, 95 percent CI 1.18 to 7.42), and homozygous and heterozygous TPMT variant allele genotype (OR 18.60, 95 percent CI 4.12 to 83.60; and 4.62, 95 percent CI 2.34 to 9.16, respectively). In general, TPMT phenotyping costs less than genotyping, although estimates across studies are quite heterogeneous.

CONCLUSIONS

There is insufficient direct evidence regarding the effectiveness of pretesting of TPMT status in patients with chronic autoimmune diseases. Indirect evidence confirms strong association of leukopenia with lower levels of TPMT activity and carrier genotype already established in the literature.

Development quality criteria to evaluate nontherapeutic studies of incidence, prevalence, or risk factors of chronic diseases: pilot study of new checklists

OBJECTIVE

To develop two checklists for the quality of observational studies of incidence or risk factors of diseases.

STUDY DESIGN AND SETTING

Initial development of the checklists was based on a systematic literature review. The checklists were refined after pilot trials of validity and reliability were conducted by seven experts, who tested the checklists on 10 articles.

RESULTS

The checklist for studies of incidence or prevalence of chronic disease had six criteria for external validity and five for internal validity. The checklist for risk factor studies had six criteria for external validity, 13 criteria for internal validity, and two aspects of causality. A Microsoft Access database produced automated standardized reports about external and internal validities. Pilot testing demonstrated face and content validities and discrimination of reporting vs. methodological qualities. Interrater agreement was poor. The experts suggested future reliability testing of the checklists in systematic reviews with preplanned protocols, a priori consensus about research-specific quality criteria, and training of the reviewers.

CONCLUSION

We propose transparent and standardized quality assessment criteria of observational studies using the developed checklists. Future testing of the checklists in systematic reviews is necessary to develop reliable tools that can be used with confidence.

Development quality criteria to evaluate nontherapeutic studies of incidence, prevalence, or risk factors of chronic diseases: pilot study of new checklists

OBJECTIVE

To develop two checklists for the quality of observational studies of incidence or risk factors of diseases.

STUDY DESIGN AND SETTING

Initial development of the checklists was based on a systematic literature review. The checklists were refined after pilot trials of validity and reliability were conducted by seven experts, who tested the checklists on 10 articles.

RESULTS

The checklist for studies of incidence or prevalence of chronic disease had six criteria for external validity and five for internal validity. The checklist for risk factor studies had six criteria for external validity, 13 criteria for internal validity, and two aspects of causality. A Microsoft Access database produced automated standardized reports about external and internal validities. Pilot testing demonstrated face and content validities and discrimination of reporting vs. methodological qualities. Interrater agreement was poor. The experts suggested future reliability testing of the checklists in systematic reviews with preplanned protocols, a priori consensus about research-specific quality criteria, and training of the reviewers.

CONCLUSION

We propose transparent and standardized quality assessment criteria of observational studies using the developed checklists. Future testing of the checklists in systematic reviews is necessary to develop reliable tools that can be used with confidence.

Complementary and alternative therapies for back pain II

BACKGROUND

Back and neck pain are important health problems with serious societal and economic implications. Conventional treatments have been shown to have limited benefit in improving patient outcomes. Complementary and Alternative Medicine (CAM) therapies offer additional options in the management of low back and neck pain. Many trials evaluating CAM therapies have poor quality and inconsistent results.

OBJECTIVES

To systematically review the efficacy, effectiveness, cost-effectiveness, and harms of acupuncture, spinal manipulation, mobilization, and massage techniques in management of back, neck, and/or thoracic pain.

DATA SOURCES

MEDLINE, Cochrane Central, Cochrane Database of Systematic Reviews, CINAHL, and EMBASE were searched up to 2010; unpublished literature and reference lists of relevant articles were also searched. study selection: All records were screened by two independent reviewers. Primary reports of comparative efficacy, effectiveness, harms, and/or economic evaluations from randomized controlled trials (RCTs) of the CAM therapies in adults (age ≥ 18 years) with back, neck, or thoracic pain were eligible. Non-randomized controlled trials and observational studies (case-control, cohort, cross-sectional) comparing harms were also included. Reviews, case reports, editorials, commentaries or letters were excluded.

DATA EXTRACTION

Two independent reviewers using a predefined form extracted data on study, participants, treatments, and outcome characteristics.

RESULTS

265 RCTs and 5 non-RCTs were included. Acupuncture for chronic nonspecific low back pain was associated with significantly lower pain intensity than placebo but only immediately post-treatment (VAS: -0.59, 95 percent CI: -0.93, -0.25). However, acupuncture was not different from placebo in post-treatment disability, pain medication intake, or global improvement in chronic nonspecific low back pain. Acupuncture did not differ from sham-acupuncture in reducing chronic non-specific neck pain immediately after treatment (VAS: 0.24, 95 percent CI: -1.20, 0.73). Acupuncture was superior to no treatment in improving pain intensity (VAS: -1.19, 95 percent CI: 95 percent CI: -2.17, -0.21), disability (PDI), functioning (HFAQ), well-being (SF-36), and range of mobility (extension, flexion), immediately after the treatment. In general, trials that applied sham-acupuncture tended to produce negative results (i.e., statistically non-significant) compared to trials that applied other types of placebo (e.g., TENS, medication, laser). Results regarding comparisons with other active treatments (pain medication, mobilization, laser therapy) were less consistent Acupuncture was more cost-effective compared to usual care or no treatment for patients with chronic back pain. For both low back and neck pain, manipulation was significantly better than placebo or no treatment in reducing pain immediately or short-term after the end of treatment. Manipulation was also better than acupuncture in improving pain and function in chronic nonspecific low back pain. Results from studies comparing manipulation to massage, medication, or physiotherapy were inconsistent, either in favor of manipulation or indicating no significant difference between the two treatments. Findings of studies regarding costs of manipulation relative to other therapies were inconsistent. Mobilization was superior to no treatment but not different from placebo in reducing low back pain or spinal flexibility after the treatment. Mobilization was better than physiotherapy in reducing low back pain (VAS: -0.50, 95 percent CI: -0.70, -0.30) and disability (Oswestry: -4.93, 95 percent CI: -5.91, -3.96). In subjects with acute or subacute neck pain, mobilization compared to placebo significantly reduced neck pain. Mobilization and placebo did not differ in subjects with chronic neck pain. Massage was superior to placebo or no treatment in reducing pain and disability only amongst subjects with acute/sub-acute low back pain. Massage was also significantly better than physical therapy in improving back pain (VAS: -2.11, 95 percent CI: -3.15, -1.07) or disability. For subjects with neck pain, massage was better than no treatment, placebo, or exercise in improving pain or disability, but not neck flexibility. Some evidence indicated higher costs for massage use compared to general practitioner care for low back pain. Reporting of harms in RCTs was poor and inconsistent. Subjects receiving CAM therapies reported soreness or bleeding on the site of application after acupuncture and worsening of pain after manipulation or massage. In two case-control studies cervical manipulation was shown to be significantly associated with vertebral artery dissection or vertebrobasilar vascular accident.

CONCLUSIONS

Evidence was of poor to moderate grade and most of it pertained to chronic nonspecific pain, making it difficult to draw more definitive conclusions regarding benefits and harms of CAM therapies in subjects with acute/subacute, mixed, or unknown duration of pain. The benefit of CAM treatments was mostly evident immediately or shortly after the end of the treatment and then faded with time. Very few studies reported long-term outcomes. There was insufficient data to explore subgroup effects. The trial results were inconsistent due probably to methodological and clinical diversity, thereby limiting the extent of quantitative synthesis and complicating interpretation of trial results. Strong efforts are warranted to improve the conduct methodology and reporting quality of primary studies of CAM therapies. Future well powered head to head comparisons of CAM treatments and trials comparing CAM to widely used active treatments that report on all clinically relevant outcomes are needed to draw better conclusions.

Hemophilic pseudotumor--is there a role of radiotherapy? Literature review and a case report

We share the literature and management of an adult with moderate hemophilia a presented with a calcaneal pseudotumor and non healing ulcer by radiation therapy, factor VIII and cryoprecipitate supplement. Numerous literatures so far have quoted the satisfactory role of radiotherapy in hemophilic pseudotumor. We found it to be of great help as our case responded with radiotherapy, factor VIII and cryoprecipitate supplement and has a satisfactory 2 years follow up.

Systematic review: comparative effectiveness and harms of combination therapy and monotherapy for dyslipidemia

BACKGROUND

Statin therapy effectively prevents vascular disease, but treatment targets are often not achieved.

PURPOSE

To compare the benefits and harms of high-dose statin monotherapy with those of combination therapy in adults at high risk for coronary disease.

DATA SOURCES

English-language records from MEDLINE (1966 to 2009), EMBASE (1980 to 2009), and the Cochrane Library (third quarter of 2008).

STUDY SELECTION

A reviewer screened records, and a second reviewer verified selection of randomized, controlled trials in adult patients that compared combinations of statins and bile-acid sequestrants, fibrates, ezetimibe, niacin, or omega-3 fatty acids with statin monotherapy, as well as nonrandomized comparative studies that were longer than 24 weeks and reported clinical and harms outcomes.

DATA EXTRACTION

Data were abstracted for studies by using standardized forms, and study quality was rated with a standardized scale and strength of evidence by using the Grading of Recommendations Assessment, Development, and Evaluation approach.

DATA SYNTHESIS

102 studies met eligibility criteria. The main analysis compared combination therapy with high-dose statin monotherapy in high-risk patients. Very-low-strength evidence showed that statin-ezetimibe (2 trials; n = 439) and statin-fibrate (1 trial; n = 166) combinations did not reduce mortality more than high-dose statin monotherapy. No trials compared the effect of combination therapy versus high-dose statin monotherapy on the incidence of myocardial infarction, stroke, or revascularization procedures. Two statin-ezetimibe trials (n = 295) demonstrated higher low-density lipoprotein cholesterol goal attainment with combination therapy (odds ratio, 7.21 [95% CI, 4.30 to 12.08]). Trials in lower-risk patients did not show a difference in mortality.

LIMITATIONS

Studies were generally short, focused on surrogate outcomes, and were heterogeneous in the sample's risk for coronary disease. Few studies examined treatment combinations other than statin-ezetimibe.

CONCLUSION

Limited evidence suggests that combinations of lipid-lowering agents do not improve clinical outcomes more than high-dose statin monotherapy. Very-low-quality evidence favors statin-ezetimibe treatment for attainment of low-density lipoprotein cholesterol goals.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality.

Oral phosphodiesterase-5 inhibitors and hormonal treatments for erectile dysfunction: a systematic review and meta-analysis

BACKGROUND

Erectile dysfunction (ED) is a common male sexual disorder. The relative benefits and harms of pharmacologic therapies for ED, as well as the value of hormonal testing in men with ED, are uncertain.

PURPOSE

To evaluate the efficacy and harms of oral phosphodiesterase-5 (PDE-5) inhibitors and hormonal treatments for ED and assess the effect of measuring serum hormone levels on treatment outcomes for ED.

DATA SOURCES

English-language studies from MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, PsycINFO, AMED, and SCOPUS through April 2009. Trial reference lists also were scanned.

STUDY SELECTION

Randomized, controlled trials (RCTs) of oral PDE-5 inhibitors and hormonal treatment for ED, and observational studies reporting measurement of serum hormone levels, prevalence of hormonal abnormalities, or both in men with ED.

DATA EXTRACTION

Two independent reviewers abstracted data on study, participant, and treatment characteristics; efficacy and harms outcomes; and prevalence of hormonal abnormalities.

DATA SYNTHESIS

Data, primarily from short-term trials (<or=12 weeks), indicate that PDE-5 inhibitors were more effective than placebo in improving sexual intercourse success (69.0% vs. 35.0%). The proportion of men with improved erections was significantly greater among those treated with PDE-5 inhibitors (range, 67.0% to 89.0%) than with placebo (range, 27.0% to 35.0%). The PDE-5 inhibitors were associated with increased risk for any adverse events compared with placebo (for example, relative risk with sildenafil, 1.72 [95% CI, 1.53 to 1.93]). In 4 head-to-head RCTs comparing sildenafil, vardenafil, and tadalafil, improvement of ED and adverse events did not differ among treatments. Results from 15 RCTs evaluating hormonal treatment of ED were inconsistent on whether treatment improved outcomes. Evidence was insufficient regarding whether men with ED had a higher prevalence of hypogonadism than men without ED.

LIMITATIONS

Many RCTs were of low methodological and reporting quality, particularly those involving hormonal treatments or directly comparing different PDE-5 inhibitors. Most RCTs provided only short-term efficacy and harms data.

CONCLUSION

Oral PDE-5 inhibitors improved erectile functioning and had similar efficacy and safety profiles. Results on the efficacy of hormonal treatments and the value of hormone testing in men with ED were inconclusive.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality.

Surveillance search techniques identified the need to update systematic reviews

OBJECTIVE

This article reports on literature surveillance methods to identify new evidence eligible for updating systematic reviews.

STUDY DESIGN AND SETTING

Five surveillance search approaches are tested in the context of identifying studies that would signal major or invalidating new evidence for existing systematic reviews of health care interventions. Recall for each search approach was assessed as proportion of a composite yield of relevant studies across all search approaches that were identified by that approach. Screening burden was the number of studies that would need to be reviewed to identify the evidence that would necessitate updating.

RESULTS

Searches were tested in a cohort of 77 systematic reviews. No one method yielded consistently high recall of relevant new evidence, so combinations of the strategies were examined. A search algorithm based on PubMed's related article search in combination with a subject searching using clinical queries was the most effective combination, retrieving all relevant new records in 68 cases. Screening burden was a median of 71 new records per review (inter-quartile range: 42-161).

CONCLUSION

Surveillance for emerging evidence that signals the need to update systematic reviews is feasible using a combination of subject searching and searching based on the PubMed's related article function.

How quickly do systematic reviews go out of date? A survival analysis

BACKGROUND

Systematic reviews are often advocated as the best source of evidence to guide clinical decisions and health care policy, yet we know little about the extent to which they require updating.

OBJECTIVE

To estimate the average time to changes in evidence that are sufficiently important to warrant updating systematic reviews.

DESIGN

Survival analysis of 100 quantitative systematic reviews.

SAMPLE

Systematic reviews published from 1995 to 2005 and indexed in ACP Journal Club. Eligible reviews evaluated a specific drug or class of drug, device, or procedure and included only randomized or quasi-randomized, controlled trials.

MEASUREMENTS

Quantitative signals for updating were changes in statistical significance or relative changes in effect magnitude of at least 50% involving 1 of the primary outcomes of the original systematic review or any mortality outcome. Qualitative signals included substantial differences in characterizations of effectiveness, new information about harm, and caveats about the previously reported findings that would affect clinical decision making.

RESULTS

The cohort of 100 systematic reviews included a median of 13 studies and 2663 participants per review. A qualitative or quantitative signal for updating occurred for 57% of reviews (95% CI, 47% to 67%). Median duration of survival free of a signal for updating was 5.5 years (CI, 4.6 to 7.6 years). However, a signal occurred within 2 years for 23% of reviews and within 1 year for 15%. In 7%, a signal had already occurred at the time of publication. Only 4% of reviews had a signal within 1 year of the end of the reported search period; 11% had a signal within 2 years of the search. Shorter survival was associated with cardiovascular topics (hazard ratio, 2.70 [CI, 1.36 to 5.34]) and heterogeneity in the original review (hazard ratio, 2.15 [CI, 1.12 to 4.11]).

LIMITATION

Judgments of the need for updating were made without involving content experts.

CONCLUSION

In a cohort of high-quality systematic reviews directly relevant to clinical practice, signals for updating occurred frequently and within a relatively short time.

The association between seated immobility and local lower-limb venous coagulability in healthy adult volunteers: a simulation of prolonged travel immobility

This is the first study to examine the hypothesis that prolonged sitting is associated with procoagulant changes in the local lower-limb venous system. A comparison was made with upper-limb venous changes. Changes in markers of thrombin generation, fibrinolysis, endothelial perturbation and haemoconcentration were analysed as 10 healthy adult male participants sat for 8 h. The change in foot volume was estimated. Subjective venous thromboembolism assessment was undertaken hourly, along with 2-week and 4-week safety follow-up for clinical events. Expected increases in median prothrombin fragments 1 and 2, thrombin-antithrombin complex and D-dimer were not observed in either limb. An increase greater than 45% in the median tissue plasminogen activator and plasminogen activator-1 molar ratio (t-PA/PAI-1), and a decrease greater than 15% in median soluble thrombomodulin were noted in both limbs. Median haematocrit decreased minimally (1%) in the lower limbs, while the foot volume increased by 4%. Subjects experienced vague symptoms after 6 h of sitting, but none developed symptomatic venous thromboembolism. Upper and lower-limb changes in biomarkers did not correlate, except those in t-PA/PAI-1 ratio and plasminogen activator-1. Significant correlation was found between changes in the lower-limb t-PA/PAI-1 ratio and right foot volume. This study originally reveals that even in the lower limbs, prolonged daytime cramped sitting is not associated with significant procoagulant changes in healthy adult male volunteers, and confirms a previous observation that local lower-limb venous changes are not identically reflected in the upper limbs.

Prolonged seated immobility-associated venous coagulability in a factor V Leiden heterozygote: a case-comparative study

Prolonged sitting and thrombophilia may compound the risk of venous thromboembolism. In order to investigate suspected local lower limb venous procoagulant changes associated with prolonged sitting-induced venous stasis in a man heterozygous for factor V Leiden (participant X), we qualitatively compared venous coagulability in lower and upper limb plasma in this participant and three other male Caucasians over 8 h of sitting. Of the four participants, participant X had the highest baseline values of prothrombin fragments 1 and 2, thrombin-antithrombin III complexes, tissue plasminogen activator, plasminogen activator inhibitor 1, D-dimer and soluble thrombomodulin. Over time, in participant X, venous prothrombin fragments 1 and 2, thrombin-antithrombin III complexes, and soluble thrombomodulin decreased in both limbs; D-dimer decreased in the lower limbs but increased in the upper limbs; the tissue plasminogen activator/plasminogen activator inhibitor 1 molar ratio increased in both limbs; and minimal changes were noted in haematocrit. A foot volume increase was associated with vague symptoms towards the end of the study. Overall, these changes were similar to those observed in other participants. It is concluded from this case comparison that prolonged sitting of 8 h duration under normal atmospheric conditions did not result in local, as well as systemic, procoagulant haemostatic responses in a heterozygote for factor V Leiden when compared with other healthy volunteers. However, this observed, possibly adaptive, response is more likely to be compromised in factor V Leiden subjects during continued or increased venous endothelial stress or in the presence of other venous thromboembolism risk factors.

Traveler's thrombosis: a systematic review

BACKGROUND

Anecdotal evidence suggests a possible link between travel and venous thromboembolism (VTE). We systematically evaluated the evidence from observational studies.

METHODS

We searched studies evaluating the risk of venous thrombosis in relation to traveling from MEDLINE and EMBASE up tp March 2004, together with a hand search of reference lists from retrieved literature, and we contacted some of the experts. Observational studies estimating the risks of VTE and isolated calf vein thrombosis were eligible. Methodologic quality was assessed based on prior criteria, and meta-analysis was considered where applicable.

RESULTS

A total of 194 English-language publications were initially identified. Sixteen studies were included: 9 case-control, 2 prospective controlled, and 5 other observational studies. They differed drastically in study designs, selection of controls where applicable, mode and duration of travel, and subtypes of VTE under consideration. Ten studies concluded that travel, mostly through air and of prolonged duration, is a risk factor for venous thrombosis and/or pulmonary embolism, and the risk increases for passengers with preexisting venous thrombosis risk factors. Outcomes examined ranged from asymptomatic isolated calf muscle vein thrombosis to severe fatal pulmonary embolism.

CONCLUSIONS

Current literature is controversial over any association between travel and VTE, and although the quality and power of these studies have been variable, studies of higher quality have shown a strong and significant association between prolonged air travel and VTE. No conclusions could be drawn about other modes of transportation. Since VTE is a disease of multifactorial causation, those with preexisting VTE risk factors are most vulnerable.

Effect of naproxen on the pharmacokinetic parameters of rifampicin

The effect of naproxen (500 mg) on the pharmacokinetics of rifampicin (450 mg) was evaluated in healthy human subjects (n = 10). Subjects participated in a two way crossover trial, the first dosing condition was rifampicin alone (control), and the second dosing condition was naproxen with rifampicin. The concentrations of rifampicin from the serum samples were determined by HPLC. The pharmacokinetic parameters indicated a significant (P < 0.05) increase in elimination rate constant (Ke), clearance (Cl), volume of distribution (Vd), while significant decrease in the mean residence time (MRT), and area under the concentration-time curve (AUC). Insignificant increase and decrease in absorption rate constant (Ka), and elimination half-life (t1/2), time for maximum concentration (Tmax), maximum drug concentration (Cmax) respectively was observed.

Pharmacokinetic study about interaction of Naproxen and Isoniazid

Effect of Naproxen (500 mg) was studied on the pharmacokinetic characteristics of Isoniazid (300 mg) in ten healthy human volunteers in a complete crossover design. A high performance liquid chromatography (HPLC) method was used to analyze serum drug concentrations. Naproxen caused a highly significant (P<0.001) increase in AUC, significant (P<0.05) increase in elimination half life (t(1/2)) and time for the maximum drug concentration (tmax) while significant (P<0.05) decrease in elimination rate constant (Kc). Insignificant decrease and increase was observed in absorption rate constant (Ka) and maximum drug concentration (Cmax) respectively.

Organochlorine pesticide residues in human blood in the population of Multan (Pakistan)

Organochlorine pesticide residues were monitored in samples of human blood (N=32), obtained from concerned volunteers suspecting oral, dermal, or inhalation exposure to Endosulfan and Heptachlor, either environmentally, or occupationally, either recently or in the recent past of Multan Division, (Pakistan) during 1995-96. The pesticide residues were extracted with n-hexane; detection and quantification was performed by gas chromatography (Shimadzu GC 14-A) with a 63Ni-Electron Capture Detector (ECD). Residues of Endosulfan were found higher as compared to Heptachlor in all samples. The highest concentration of Endosulfan residues in blood in the population of Multan and Mailsi regions was 90.29 g/kg and 82.14 g/kg, lowest as 58.13 g/kg and 60.13 g/kg while Heptachlor had highest level as 12.978 g/kg and 9.997 g/kg, minimum as 0.37 g/kg and 1.23 g/kg respectively.