Proinflammatory and cytotoxic effects of Mexico City air pollution particulate matter in vitro are dependent on particle size and composition

Exposure to urban airborne particulate matter (PM) is associated with adverse health effects. We previously reported that the cytotoxic and proinflammatory effects of Mexico City PM10 (less than or equal to 10 micro m mean aerodynamic diameter) are determined by transition metals and endotoxins associated with these particles. However, PM2.5 (less than or equal to 2.5 micro m mean aerodynamic diameter) could be more important as a human health risk because this smaller PM has the potential to reach the distal lung after inhalation. In this study, we compared the cytotoxic and proinflammatory effects of Mexico City PM10 with those of PM2.5 using the murine monocytic J774A.1 cell line in vitro. PMs were collected from the northern zone or the southeastern zone of Mexico City. Elemental composition and bacterial endotoxin on PMs were measured. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) production by J774A.1 cells was measured in the presence or absence of recombinant endotoxin-neutralizing protein (rENP). Both northern and southeastern PMs contained endotoxin and a variety of transition metals. Southeastern PM10 contained the highest endotoxin levels, 2-fold higher than that in northern PM10. Northern and southeastern PM2.5 contained the lowest endotoxin levels. Accordingly, southeastern PM10 was the most potent in causing secretion of the proinflammatory cytokines TNF-alpha and IL-6. All PM2.5 and PM10 samples caused cytotoxicity, but northern PMs were the most toxic. Cytokine secretion induced by southeastern PM10 was reduced 50-75% by rENP. These results indicate major differences in PM10 and PM2.5. PM2.5 induces cytotoxicity in vitro through an endotoxin-independent mechanism that is likely mediated by transition metals. In contrast, PM10 with relatively high levels of endotoxin induces proinflammatory cytokine release via an endotoxin-dependent mechanism.     

Systematic Review of Health Economic Impact Evaluations of Risk Prediction Models: Stop Developing,Start Evaluating

Background

Although health economic evaluations (HEEs) are increasingly common for therapeutic interventions, they appear to be rare for the use of risk prediction models (PMs).

A prospective randomized, comparative, open-label trial of the safety and efficacy of paromomycin (aminosidine) plus sodium stibogluconate versus sodium stibogluconate alone for the treatment of visceral leishmaniasis

Response to treatment with organic pentavalent antimonials, the standard first-line treatment for visceral leishmaniasis (VL), has been decreasing since their introduction into India. Combining sodium stibogluconate (SB) with paromomycin (PM) may be an efficient alternative to single-agent therapy. This trial was designed to assess the safety and efficacy of PM 12 or 18 mg/kg daily plus SB 20 mg/kg daily for 21 days compared to SB alone for 30 days. One hundred and fifty patients were randomly assigned in 1996 to 1 of the 3 treatments and followed-up for 180 days. At the end of treatment, 49 of 52 patients receiving PM12 + SB, 46 of 48 receiving PM18 + SB, and 27 of 49 patients receiving SB alone, were cured. During follow-up there was 1 relapse in each of the treatment groups, giving final cure rates of 48 of 52 (92.3%) for PM12 + SB, 45 of 48 (93.8%) for PM18 + SB, and 26 of 49 (53.1%) for SB. PM plus SB for 21 days at either 12 or 18 mg/kg daily was significantly more effective than SB alone for 30 days (chi 2 P < 0.001). One patient (SB alone) had experienced a serious adverse event: cardiotoxicity at day 8 (myocarditis and ECG changes) which caused withdrawal from the study. Only 19 of 100 patients enrolled in the PM treatment arms had a complete audiogram series conducted thus making it difficult to assess oto-toxicity. PM 12 or 18 mg/kg daily plus a standard dose of SB for 21 days was statistically more effective than SB in producing a final cure for patients with VL in Bihar, India.     

Opinions of women with high inherited breast cancer risk about prophylactic mastectomy: an initial evaluation from a screening trial including magnetic resonance imaging and ductal lavage

OBJECTIVE: Prophylactic mastectomy (PM) is often considered, but variably chosen by women at high inherited risk of breast cancer; few data exist on patient tolerance of intensive breast screening as an alternative to PM. We performed an evaluation of high-risk women's tolerance of a breast screening protocol using clinical breast examination, mammography, breast magnetic resonance imaging (MRI) and ductal lavage (DL), and of change in attitudes toward PM after screening. DESIGN: A questionnaire assessing tolerance of screening procedures and change in opinion towards PM was designed and administered to 43 study participants, after a median follow-up of 13 months. Responses were evaluated according to patient characteristics, including type of study-prompted interventions, BRCA mutation status, and prior history of cancer, via univariate analysis. RESULTS: Most patients [85.3% (68.9-95.1%)] were more opposed or unchanged in their attitudes towards PM after study participation, with only 14.7% (5.0-31.1%) less opposed (P = 0.017) despite a short-interval follow-up MRI rate of 71.7% and a biopsy rate of 37%. Lower rates of maximal discomfort were reported with mammogram [2.8% (0-14.5%)] and MRI [5.6% (0-18.7%)] than with DL [28.6% (14.6-46.3%)], with P = 0.035. CONCLUSIONS: Most high-risk women tolerated intensive breast screening well; they were not more inclined towards PM after participating. Future studies should prospectively evaluate larger numbers of high-risk women via multivariate analysis, to determine characteristics associated with preference for breast screening vs. PM.     

Diffusion flame-derived fine particulate matters doped with iron caused genotoxicity in B6C3F1 mice

Potential genotoxic effects of diffusion flame-derived particulate matters (PMs), known to cause various adverse health problems, doped with iron, one of the representative heavy metals frequently found in the atmosphere, were examined. B6C3F1 mice were exposed to PMs [chamber 1 (low), 100; chamber 2 (middle), 200; and chamber 3 (high), 400 microg/m3] for 6 h/day, 5 days/week for one, two and four weeks in 1.5 m3 whole-body inhalation chambers. Our diffusion flame system produced 94.8 and 5.2% fine PM2.5 and PM10, respectively, with 89% of PM2.5 sized between 0.1 and 0.2 microm. Two cytogenetic endpoints were investigated through chromosomal aberration and supravital micronucleus (SMN) assays. Frequencies of cells with chromosome aberration (%) were observed in time- and concentration-dependent manners except in one-week exposure group, as also observed in SMN study. Generally, noniron flame induced less chromosome aberration than iron-doped flame, an indication that iron particles could potentiate urban PM toxicity. The above results indicate our diffusion flame system generated genotoxic fine PMs, whose effects were potentiated by organometallic particles such as iron. Our system can provide reliable PM models for studying the toxicity of urban fine PMs applicable for risk assessment.     

In vitro and in vivo study of electromagnetic compatibility of cellular phones and pacemakers]

Electromagnetic compatibility (EMC) of cellular phones and pacemakers (PM) was examined in four different cellular phone system (NMT, GSM, RLL, DCS 1800 MHz) and in fifteen different PM type in-vitro and in-vivo in humans. After more than 1100 in-vitro and 130 in-vivo tests we concluded, that the electromagnetic immunity of the PMs which are implanted in Hungary is suitable with only few exceptions. The highest rate of EMC problems was observed with NMT 450 MHz cellular phones (10.5%-63%). There was no EMC disturbance observed with GSM and DCS 1800 MHz cellular phones. There was only one case when clinically significant symptom was noticed with only one PM type and with NMT system cellular phone when the distance of cellular phone was 3-4 cms, and the power was maximal. There was not any EMC disturbance observed with none of the cellular phone systems during normal talking and when the distance of the PM and cellular phone was more than 20 cms. Our study supports guidelines which suggest that PM patients should contact their physicians when using cellular phones and cellular phones and PMs should not get closer than 20 cms.     

Classification of findings in mammography screening--a method to minimise recall anxiety?

STUDY OBJECTIVE--The aim was to find out if it is possible, by classifying screening mammograms according to the likelihood of malignancy, to divide the recalled women to a group in which there is high suspicion of malignancy, most having breast cancers, and a group with more obscure findings. DESIGN--Screening mammograms of recalled women were classified according to the likelihood of malignancy. 0 = technically insufficient, 1 = normal, 2 = benign tumour, 3 = malignancy cannot be excluded, 4 = strongly suspicious for malignancy, 5 = malignant. SETTING--This study was a population based survey of mammography screening in Helsinki and surroundings in Finland. PATIENTS--21,417 women (aged 50-59 years) were invited to be screened, 18,012 (84.10%) participated. Of these 579 (3.21% of those screened) were recalled for further studies; 124 of these were referred for surgical biopsy and 82 had breast cancer. MEASUREMENTS AND MAIN RESULTS--All cases classified as 5, 60% of the cases classified as 4, 6.5% of the cases classified as 3, 0% of the cases classified as 2 or 1, and 1.2% of the cases classified as 0 proved to have breast cancers. However classification 5 represented 5.9% of all recalled women and 41.5% of all screening detected breast cancers; classification 4, 6.0% of all recalled women and 25.6% of all screening detected breast cancers; classification 3, 68.9% of all recalled women and 31.7% of all screening detected breast cancers; classification 2, 11.7% and classification 1, 2.9% of all recalled women. No breast cancers were detected with these classifications. Classification 0 represented 4.5% of all recalled women and 1.2% of all screening detected breast cancers. Classifications 5 and 4 represented only 11.9% of all recalled women but 67.1% of all screening detected breast cancers. CONCLUSIONS--By classifying screening mammograms according to the likelihood of malignancy, recalled women can be divided into two groups: (1) a quite small subgroup in which everyone or almost everyone will be shown to have breast cancer; and (2) a much larger subgroup in which only a few will be proven to have breast cancer. The invitation procedure for the further studies should be improved on this basis of minimising anxiety among recalled women.     

Telecardiology: one-lead electrocardiogram monitoring and nurse triage in chronic heart failure

We investigated a home-based intervention based on telecardiology in patients with chronic heart failure (CHF). Two hundred and thirty CHF patients, aged 59 years (SD 9), in stable condition and with optimized therapy were enrolled. The programme consisted of trans-telephonic follow-up and electrocardiogram (ECG) monitoring followed by visits from a paramedical and medical team. The patient could call the centre when required (tele-assistance), while the team could call the patient at prescheduled times (telemonitoring). During the first 12 months, there were 3767 calls (873 ad hoc and 2894 scheduled calls). There were 648 events, including 126 episodes of asymptomatic hypotension and 168 episodes which were not due to cardiological symptoms. No actions were taken by the nurse after 2417 calls (64%). A change in therapy was suggested after 418 calls, hospital admission in 62 patients, further investigations for 243 patients and a consultation with the general practitioner in 41 patients. A total of 2303 one-lead ECG recordings were received (10 per patient); 126 recordings (6%) were diagnosed as pathological in comparison with the baseline one. The one-lead ECG recording was used for titration of beta-blockers in 79 patients (mean dosage 38 mg vs 42 mg, P<0.01). Home telenursing could be an important application of telemedicine and single-lead ECG recording seems to offer additional benefit in comparison with telephone follow-up alone.     

Psychological distress as a risk factor for coronary heart disease in the Whitehall II Study

BACKGROUND: Psychiatric disorder and psychological distress are increasingly recognized as risk factors for coronary heart disease (CHD). Elucidation of the mechanisms of these associations has implications for prevention. This study aims to confirm the association between psychological distress and CHD and examine if it could be explained by other factors such as health behaviours, social isolation and low control at work. METHODS: A prospective occupational cohort study of London-based civil service employees (Whitehall II Study) with baseline data collected from 1985-1988 with a 5-year follow-up. The participants were male and female middle-aged civil servants working in 20 Government Departments; 73% of eligible employees attended baseline screening. Psychological distress measured by the General Health Questionnaire (GHQ) at baseline was used to predict incidence of self-reported CHD and possible and probable electrocardiographic (ECG) abnormalities during follow-up. RESULTS: In men, baseline psychological distress was associated with an increased incidence of overall self-reported CHD (odds ratios [OR] = 1.83, 95% CI : 1.5-2.3) and ECG abnormalities (OR = 1.51, 95% CI : 1.1-2.1), after adjustment for age, employment grade and length of follow-up. In women, baseline psychological distress was also associated with an increased incidence of CHD (OR = 1.60, 95% CI : 1.2-2.1), but not with ECG abnormalities. Adjustment for health behaviours, marital status, social networks and work characteristics reduced the risks for incident CHD by 12% in men and by 10% in women; for ECG abnormalities these adjustments increased the risk in men by 16% and had little effect in women. CONCLUSIONS: The experience of psychological distress confers increased risk of CHD in men that is not explained by health behaviours, social isolation or work characteristics. The increased risk of CHD associated with psychological distress is not consistently demonstrated in women.     

Long-term Prognostic Value of Major and Minor ECG Abnormalities in Latent Keshan Disease With Suspect Chronic Keshan Disease

Objective

This study aims to determine whether baseline electrocardiography (ECG) abnormalities, the appearance of new ECG abnormalities, or other clinical characteristics are associated with increased rates of progression to chronic Keshan disease (KD) among patients with latent KD.

Methods

Four hundred and fourteen new latent KD patients from a monitored population in China were diagnosed and then followed for 10 years. Baseline and 10-year ECG abnormalities were classified according to the Minnesota Code as major and minor. Using Cox proportional hazards regression models, the addition of ECG abnormalities to traditional risk factors were examined to predict chronic KD events.

Results

In 414 latent KD patients with ECG abnormalities, 220 (53.1%) had minor and 194 (46.9%) had major ECG abnormalities. During the follow-up, 92 (22.2%) patients experienced chronic KD events; 32 (14.5%) and 60 (30.9%) of these chronic KD events occurred in the minor and major ECG abnormalities groups, respectively. After adjustment for baseline potential confounders, the hazard ratios and 95% confidence intervals (CIs) for progression to chronic KD in latent KD patients with major ECG abnormalities versus those with minor ECG abnormalities was 2.43 (95% CI 1.58–3.93).

Conclusions

Major ECG abnormalities and new ventricular premature complex abnormalities that occurred during the follow-up were both associated with an increased risk of progression to chronic KD. Atrial fibrillation and right bundle branch block with left anterior hemiblock are the most strongly predictive components of major ECG abnormalities. Depending on the model, adding ECG abnormalities to traditional risk factors was associated with improved risk prediction in latent KD.Key words: Keshan disease, selenium, electrocardiogram     

Less pap-2 results ('minor abnormalities') in the population screening for cervical cancer since the introduction of new guidelines in 1996

OBJECTIVE: To determine whether the 1996 implementation of new guidelines for the classification and management of cervical smears in the Dutch population screening programme for cervical cancer (i.e. inflammatory symptoms are no longer classified as moderate dysplasia and women with two smears with moderate dysplasia are referred directly to the gynaecologist) was followed by a reduction in both the number of women with repeat smears and the length of follow-up. METHODS: The results of all smears of women aged 35-54 years from 1990 onwards, were retrieved from the Dutch Network and National Database for Pathology (PALGA). The percentage of smears with moderate dysplasia was analysed with respect to time. The percentage of women with a histological examination during the follow-up phase of the population screening programme (1990 and 1991) was compared with that for the new screening programme (1996). RESULTS: Following the implementation of the new guidelines, the percentage of smears with moderate dysplasia was reduced from 10% to 2%. The percentage of women with a histological examination during the follow up of two smears with moderate dysplasia remained the same. The new recommendations for additional smears were not followed: for 28% no repeat smear was available after 2.25 years versus 10% in 1992. There were indications that the referral of women with two cases of moderate dysplasia to a gynaecologist was not strictly adhered to either. Since the introduction of the new guidelines, the estimated percentage of women that should be referred to the gynaecologist following smears with moderate dysplasia has not changed. CONCLUSION: The new recommendations have lead to fewer smears being classified as moderate dysplasia. The long-term effects, such as a reduction in the length of the follow-up period, can only be analysed in a few years time.     

Patient follow-up after participating in a beach-based skin cancer screening program

Many skin cancer screenings occur in non-traditional community settings, with the beach being an important setting due to beachgoers being at high risk for skin cancer. This study is a secondary analysis of data from a randomized trial of a skin cancer intervention in which participants (n = 312) had a full-body skin examination by a clinician and received a presumptive diagnosis (abnormal finding, no abnormal finding). Participants' pursuit of follow-up was assessed post-intervention (n = 283). Analyses examined: (1) participant's recall of screening results; and (2) whether cognitive and behavioral variables were associated with follow-up being as advised. Just 12% of participants (36/312) did not correctly recall the results of their skin examination. One-third (33%, 93/283) of participants' follow-up was classified as being not as advised (recommend follow-up not pursued, unadvised follow-up pursued). Among participants whose follow-up was not as advised, 71% (66/93) did not seek recommended care. None of the measured behavioral and cognitive variables were significantly associated with recall of screening examination results or whether follow-up was as advised. Research is needed to determine what factors are associated with follow-up being as advised and to develop messages that increase receipt of advised follow-up care.     

Improving nutritional screening of hospitalized patients: the role of prealbumin

BACKGROUND: Limited resources prevent hospitals from having all patients formally evaluated by a nutrition expert. Thus, hospitals rely on nutrition-screening tools to identify malnourished patients. The purpose of this study was to determine the effectiveness of a nutrition-screening protocol, prealbumin (PAB), retinol binding protein (RBP), and albumin (ALB) in identifying malnourished hospitalized patients. METHODS: A nutrition screening protocol was prospectively used in medical and surgical patients and consisted of a nurse administering a questionnaire to patients and requesting formal evaluation by a registered dietitian (RD) only if nutritional issues were identified. Patients also had ALB, PAB, and RBP drawn, which were used to both screen and identify the malnourished. PAB, RBP, and ALB were compared as predictors of RD classification of patient nutritional status. RESULTS: The nutrition-screening protocol classified 104 of 320 patients (33%) as malnourished. However, 43% of the patients were not deemed at nutritional risk according to this protocol and therefore did not receive RD assessment. PAB was a significant predictor of RD-determined nutritional status (p < .05), whereas RBP and ALB were not. PAB screening/assessment identified 50% (162/320) of the patients as being malnourished. Notably, 50% of the patients (71 of 142) who were not evaluated by an RD were identified as malnourished using PAB criteria. The nutrition-screening protocol took 1.2 days longer to determine malnourishment compared with PAB (p = .0021). CONCLUSIONS: Use of screening questionnaires may miss or delay identification of malnourished patients. PAB screening/assessment may improve identification of those patients requiring nutrition intervention and thus enhance the care of hospitalized individuals.     

Prayer Marks in Immigrants from Bangladesh with Diabetes Who Live in Greece

Prayer marks (PMs) are commonly occurring dermatologic changes in muslims who pray and develop over a long period of time as a consequence of repeated and extended pressure. PMs need careful examination especially for patients with diabetes, who are more vulnerable due to predisposing factors such as venous insufficiency and peripheral neuropathy. A total of 166 patients with diabetes (150 males, 16 females) and 65 normal subjects from Bangladesh were examined for the appearance of PMs. Twenty-eight patients (16.9 %) and one normal subject (1.5 %) had PMs. The marks were not itchy or painful and they were observed on the dorsal aspect of the left foot, which was attributed to a more typical prayer position that placed pressure on the left foot. PMs are not a rare clinical entity among muslim patients with diabetes and most clinicians should be aware of it as it can be the predominant cause of an ulcer.     

输卵管注药绝育术有效性安全性五年随访研究

研究设计采用多中心随机化临床试验,1705例合格受术对象被随机分配使用两种粘堵剂,867例使用8％阿的平苯酚糊剂(PAP),838例使用显影苯酚胶浆(PM)。两组受术对象人口学特征、妇科检查结果和术时情况均衡可比。五年随访率分别为97.5％和98.1％。多终点递减率生命表法分析表明,两组间各顺序月的粗累积失败率经log-rank检验均有显著差异。第60个顺序月的粗累积失败率,PAP组为4.61％,PM组为11.87％。PAP的节育效果显著优于PM。97.7％受术对象做了宫颈刮片检查,均未查见可疑癌细胞或癌细胞。同时,也未发现与粘堵剂可能有关的潜在疾患。这可能由于注入每侧输卵管内的粘堵剂的剂量(0.08ml)甚微之故。五年随访结果进一步表明,该术是一种简便、安全、有效的女性绝育术。作者建议在进一步改进粘堵剂配制、规范手术操作和加强施术技术标准化管理的基础上适时地推广这项新技术。     

A pilot study of nurse-led, home-based telecardiology for patients with chronic heart failure

We assessed the feasibility of home-based telecardiology for patients with chronic heart failure (CHF). Seventy-four CHF patients were enrolled into a programme of telephone follow-up and single-lead electrocardiography (ECG) monitoring. The patients transmitted their ECG data by fixed telephone line to a receiving station, where a nurse was available for an interactive teleconsultation. Patients were followed up for a mean (SD) of 307 (108) days; 1467 calls were analysed (213 ad hoc consultations and 1254 scheduled consultations). A total of 124 cardiovascular events were recorded. Modifications to therapy were suggested in response to 119 calls; hospital admissions were suggested for 13 patients, further investigations for 7 and a consultation with the patient's general practitioner for 13. No action was taken after 1330 calls. Twenty-two ECG abnormalities were recorded. In 63 patients receiving the beta-blocker carvedilol, the mean dosage increased from 36 to 42 mg. In the previous year there were 1.8 hospitalizations per patient, while in the follow-up period there were 0.2 hospitalizations per patient. Following up CHF patients using a nurse-led telecardiology programme seems to be feasible and useful.     

The effects of particulate matter on atopic dermatitis symptoms are influenced by weather type: Application of spatial synoptic classification (SSC)

The effects of weather and air pollution on atopic dermatitis (AD) flares have not been well investigated. To investigate the effects of particulate matter (PM) on AD symptoms by weather type, a total of 125 young children (76 boys and 49 girls) under 6 years of age with AD living in Seoul, Korea, were enrolled as a panel and followed for 17 months between August 2013 and December 2014. AD symptoms were recorded on a daily basis, including itching, sleep disturbance, erythema, dry skin, oozing, and edema. Daily weather was classified into 7 categories according to spatial synoptic classification (SSC). Personal exposure to PM with an aerodynamic diameter less than 2.5 and 10?μm (PM_2.5 and PM₁₀, respectively) in each individual was estimated with time-weighted average concentrations considering outdoor and indoor levels of PMs and time to spend outdoors or indoors in a day. Generalized linear mixed models were used to analyze the effects of PM_2.5 and PM₁₀ on AD symptoms, controlling for ambient temperature, humidity, age, sex, SCORAD (SCORing of AD) at enrollment, fever, day of week, and topical corticosteroid use. A total of 20,168 person-days of symptom records were collected. The presence of AD symptoms was higher on dry polar (DP) days (45.4%, P?<?.0001) than on moist tropical (MT) days (37.7%, P < .0001). Overall, the risk of AD symptoms significantly increased with increased exposure to PM_2.5 and PM₁₀. Among the 7 weather types, the risks of AD symptoms caused by PM_2.5 and PM₁₀ exposure were significantly increased on dry moderate (DM) days, while not significant on the other weather types. In addition, lagged effect of PM_2.5 up to 4 days was found on DM days. In conclusion, dry moderate weather type, particulate matters, and their modifying effects should be simultaneously considered for proper management of AD.     

Follow-up of asbestosis patients and predictors for radiographic progression

Objective: We followed a group of 85 Finnish asbestosis patients radiographically for an average of 6.5 (range 2–10) years to examine the progression of the disease and to assess possible explanations for the progression. Methods: The examinations included full-size chest radiographs and a blood specimen analysis. The radiographs were classified according to the 1980 International Labor Office (ILO) classification. Progression was accepted if the second or third radiography was estimated (in a side-by-side comparison) to have more profusion of small opacities qualitatively than the first, even if the radiographs were classified into the same profusion category. Results: In all, 38% of the patients showed progression during the follow-up period. The average progression of small opacities ranged from ILO 1/1 to ILO 2/2 (0.4 minor ILO categories/year). The asbestosis was progressive more often among the sprayers than among the insulators and asbestos factory workers [cross-tabulation, odds ratio (OR) 5.0, 95% confidence interval (95% CI) 1.2–20]. In the logistic regression model the ILO classification category at the beginning of the follow-up (OR 1.54; 95% CI 0.96–2.47), the fibronectin (OR 1.01; 95% CI 1.00–1.01) and angiotensin-converting enzyme (ACE; OR 1.10; 95% CI 1.00–1.20) levels, and the erythrocyte sedimentation rate (ESR; OR 1.05; 95% CI 1.00–1.10) were statistically associated with the radiographic progression of small opacities. Abnormalities of the pleura were found to progress more often among the patients with progressive parenchymal opacities. Conclusion: For the progression of small-opacity profusion the significant predictors in the logistic regression model were the ILO profusion category at the beginning of the follow-up period, the fibronectin level, the ACE value, and the ESR. The model correctly classified 94% of the patients with progression and 65% of those without progression. The differences in the mean values recorded for the biomarkers between the progressors and nonprogressors, however, were small and may therefore not be of any importance to the clinician. Received: 17 November 1997 / Accepted: 8 May 1998     

ECG compression: evaluation of FFT, DCT, and WT performance

This work investigates a set of ECG data compression schemes to compare their performances in compressing and preparing ECG signals for automatic cardiac arrhythmia classification. These schemes are based on transform methods such as fast Fourier transform (FFT), discrete cosine transform (DCT), wavelet transform (WT), and their combinations. Each specific transform is applied to a pre-selected data segment from the MIT-BIH database and then compression is performed in the new domain. These transformation methods are known as an important class of ECG compression techniques. The WT has been shown as the most efficient method for further improvement. A compression ratio of 7.98 to 1 has been achieved with a percent of root mean square difference (PRD) of 0.25%, indicating that the wavelet compression technique offers the best performance over the other evaluated methods.