Patient characteristics and valuation changes impact quality of life and satisfaction in total knee arthroplasty - results from a German prospective cohort study

Background

Evaluation of variations in pre- and postoperative patient reported outcomes (PRO) and the association between preoperative patient characteristics and health and satisfaction outcomes after total knee arthroplasty (TKA) may support shared decision-making in Germany. Since previous research on TKA health outcomes indicated valuation differences in longitudinal data, experienced-based population weights were used for the first time as an external valuation system to measure discrepancies between patient and average population valuation of HRQoL.

Methods

Baseline data (n = 203) included sociodemographic and clinical characteristics and PROs, measured by the EQ-5D-3 L and WOMAC. Six-month follow-up data (n = 161) included medical changes since hospital discharge, PROs and satisfaction. A multivariate linear regression analysis was performed to evaluate the relationship between preoperative patient characteristics and PRO scores. Patient acceptable symptom state (PASS) was calculated to provide a satisfaction threshold. Patient-reported health-related quality of life (HRQoL) valuations were compared with average experienced-based population values to detect changes in valuation.

Results

One hundred thirty-seven subjects met inclusion criteria. All PRO measures improved significantly. Preoperative WOMAC and EQ-5D VAS, housing situation, marital status, age and asthma were found to be predictors of postoperative outcomes. 73% of study participants valued their preoperative HRQoL higher than the general population valuation, indicating response shift. Preoperatively, patient-reported EQ-5D VAS was substantially higher than average experienced-based population values. Postoperatively, this difference declined sharply.

Approximately 61% of the patients reported satisfactory postoperative health, being mainly satisfied with results if postoperative WOMAC was ≥82.49 (change ≥20.25) and postoperative EQ-5D VAS was ≥75 (change ≥6).

Conclusion

On average, patients benefited from TKA. Preoperative WOMAC and EQ-5D VAS were predictors of postoperative outcomes after TKA. Particularly patients with high absolute preoperative PRO scores were more likely to remain unsatisfied. Therefore, outcome prediction can contribute to shared-decision making. Using general population valuations as a reference, this study underlined a discrepancy between population and patient valuation of HRQoL before, but not after surgery, thus indicating a potential temporary response shift before surgery.

Cost-effectiveness of increasing the reach of smoking cessation interventions in Germany: results from the EQUIPTMOD

AIMS

To evaluate costs, effects and cost-effectiveness of increased reach of specific smoking cessation interventions in Germany.

DESIGN

A Markov-based state transition return on investment model (EQUIPTMOD) was used to evaluate current smoking cessation interventions as well as two prospective investment scenarios. A health-care perspective (extended to include out-of-pocket payments) with life-time horizon was considered. A probabilistic analysis was used to assess uncertainty concerning predicted estimates.

SETTING

Germany.

PARTICIPANTS

Cohort of current smoking population (18+ years) in Germany.

INTERVENTIONS

Interventions included group-based behavioural support, financial incentive programmes and varenicline. For prospective scenario 1 the reach of group-based behavioral support, financial incentive programme and varenicline was increased by 1% of yearly quit attempts (= 57 915 quit attempts), while prospective scenario 2 represented a higher reach, mirroring the levels observed in England.

MEASUREMENTS

EQUIPTMOD considered reach, intervention cost, number of quitters, quality-of-life years (QALYs) gained, cost-effectiveness and return on investment.

FINDINGS

The highest returns through reduction in smoking-related health-care costs were seen for the financial incentive programme (€2.71 per €1 invested), followed by that of group-based behavioural support (€1.63 per €1 invested), compared with no interventions. Varenicline had lower returns (€1.02 per €1 invested) than the other two interventions. At the population level, prospective scenario 1 led to 15 034 QALYs gained and €27 million cost-savings, compared with current investment. Intervention effects and reach contributed most to the uncertainty around the return-on-investment estimates. At a hypothetical willingness-to-pay threshold of only €5000, the probability of being cost-effective is approximately 75% for prospective scenario 1.

CONCLUSIONS

Increasing the reach of group-based behavioural support, financial incentives and varenicline for smoking cessation by just 1% of current annual quit attempts provides a strategy to German policymakers that improves the population's health outcomes and that may be considered cost-effective.

Costs and effects of intra-operative fluorescence molecular imaging - A model-based, early assessment

Introduction

Successful breast conserving cancer surgeries come along with tumor free resection margins and account for cosmetic outcome. Positive margins increase the likelihood of tumor recurrence. Intra-operative fluorescence molecular imaging (IFMI) aims to focus surgery on malignant tissue thus substantially lowering the presence of positive margins as compared with standard techniques of breast conservation (ST). A goal of this paper is to assess the incremental number of surgeries and costs of IFMI vs. ST.

Methods

We developed a decision analytical model and applied it for an early evaluation approach. Given uncertainty we considered that IFMI might reduce the proportion of positive margins found by ST from all to none and this proportion is assumed to be reduced to 10% for the base case. Inputs included data from the literature and a range of effect estimates. For the costs of IFMI, respective cost components were added to those of ST.

Results

The base case reduction lowered number of surgeries (mean [95% confidence interval]) by 0.22 [0.15; 0.30] and changed costs (mean [95% confidence interval]) by €-663 [€-1,584; €50]. A tornado diagram identified the Diagnosis Related Group (DRG) costs, the proportion of positive margins of ST, the staff time saving factor and the duration of frozen section analysis (FSA) as important determinants of this cost.

Conclusions

These early results indicate that IFMI may be more effective than ST and through the reduction of positive margins it is possible to save follow-up surgeries–indicating further health risk–and to save costs through this margin reduction and the avoidance of FSA.

Redefining diagnosis-related groups (DRGs) for palliative care - a cross-sectional study in two German centres

BACKGROUND

Hospital costs and cost drivers in palliative care are poorly analysed. It remains unknown whether current German Diagnosis-Related Groups, mainly relying on main diagnosis or procedure, reproduce costs adequately. The aim of this study was therefore to analyse costs and reimbursement for inpatient palliative care and to identify relevant cost drivers.

METHODS

Two-center, standardised micro-costing approach with patient-level cost calculations and analysis of the reimbursement situation for patients receiving palliative care at two German hospitals (7/2012-12/2013). Data were analysed for the total group receiving hospital care covering, but not exclusively, palliative care (group A) and the subgroup receiving palliative care only (group B). Patient and care characteristics predictive of inpatient costs of palliative care were derived by generalised linear models and investigated by classification and regression tree analysis.

RESULTS

Between 7/2012 and 12/2013, 2151 patients received care in the two hospitals including, but not exclusively, on the PCUs (group A). In 2013, 784 patients received care on the two PCUs only (group B). Mean total costs per case were € 7392 (SD 7897) (group A) and € 5763 (SD 3664) (group B), mean total reimbursement per case € 5155 (SD 6347) (group A) and € 4278 (SD 2194) (group B). For group A/B on the ward, 58%/67% of the overall costs and 48%/53%, 65%/82% and 64%/72% of costs for nursing, physicians and infrastructure were reimbursed, respectively. Main diagnosis did not significantly influence costs. However, duration of palliative care and total length of stay were (related to the cost calculation method) identified as significant cost drivers.

CONCLUSIONS

Related to the cost calculation method, total length of stay and duration of palliative care were identified as significant cost drivers. In contrast, main diagnosis did not reflect costs. In addition, results show that reimbursement within the German Diagnosis-Related Groups system does not reproduce the costs adequately, but causes a financing gap for inpatient palliative care.

Manual Compression versus Vascular Closing Device for Closing Access Puncture Site in Femoral Left-Heart Catheterization and Percutaneous Coronary Interventions: A Retrospective Cross-Sectional Comparison of Costs and Effects in Inpatient Care

OBJECTIVES

To compare complication rates, length of hospital stay, and resulting costs between the use of manual compression and a vascular closing device (VCD) in both diagnostic and interventional catheterization in a German university hospital setting.

METHODS

A stratified analysis according to risk profiles was used to compare the risk of complications in a retrospective cross-sectional single-center study. Differences in costs and length of hospital stay were calculated using the recycled predictions method, based on regression coefficients from generalized linear models with gamma distribution. All models were adjusted for propensity score and possible confounders, such as age, sex, and comorbidities. The analysis was performed separately for diagnostic and interventional catheterization.

RESULTS

The unadjusted relative risk (RR) of complications was not significantly different in diagnostic catheterization when a VCD was used (RR = 0.70; 95% confidence interval [CI] 0.22-2.16) but significantly lower in interventional catheterization (RR = 0.44; 95% CI 0.21-0.93). Costs were on average €275 lower in the diagnostic group (95% CI -€478.0 to -€64.9; P = 0.006) and around €373 lower in the interventional group (95% CI -€630.0 to -€104.2; P = 0.014) when a VCD was used. The adjusted estimated average length of stay did not differ significantly between the use of a VCD and manual compression in both types of catheterization.

CONCLUSIONS

In interventional catheterization, VCDs significantly reduced unadjusted complication rates, as well as costs. A significant reduction in costs also supports their usage in diagnostic catheterization on a larger scale.

Informing management on the future structure of hospital care: an extrapolation of trends in demand and costs in lung diseases

OBJECTIVE

The planning of health care management benefits from understanding future trends in demand and costs. In the case of lung diseases in the national German hospital market, we therefore analyze the current structure of care, and forecast future trends in key process indicators.

METHODS

We use standardized, patient-level, activity-based costing from a national cost calculation data set of respiratory cases, representing 11.9-14.1 % of all cases in the major diagnostic category "respiratory system" from 2006 to 2012. To forecast hospital admissions, length of stay (LOS), and costs, the best adjusted models out of possible autoregressive integrated moving average models and exponential smoothing models are used.

RESULTS

The number of cases is predicted to increase substantially, from 1.1 million in 2006 to 1.5 million in 2018 (+2.7 % each year). LOS is expected to decrease from 7.9 to 6.1 days, and overall costs to increase from 2.7 to 4.5 billion euros (+4.3 % each year). Except for lung cancer (-2.3 % each year), costs for all respiratory disease areas increase: surgical interventions +9.2 % each year, COPD +3.9 %, bronchitis and asthma +1.7 %, infections +2.0 %, respiratory failure +2.6 %, and other diagnoses +8.5 % each year. The share of costs of surgical interventions in all costs of respiratory cases increases from 17.8 % in 2006 to 30.8 % in 2018.

CONCLUSIONS

Overall costs are expected to increase particularly because of an increasing share of expensive surgical interventions and rare diseases, and because of higher intensive care, operating room, and diagnostics and therapy costs.

Cost-of-illness studies based on massive data: a prevalence-based, top-down regression approach

Despite the increasing availability of routine data, no analysis method has yet been presented for cost-of-illness (COI) studies based on massive data. We aim, first, to present such a method and, second, to assess the relevance of the associated gain in numerical efficiency. We propose a prevalence-based, top-down regression approach consisting of five steps: aggregating the data; fitting a generalized additive model (GAM); predicting costs via the fitted GAM; comparing predicted costs between prevalent and non-prevalent subjects; and quantifying the stochastic uncertainty via error propagation. To demonstrate the method, it was applied to aggregated data in the context of chronic lung disease to German sickness funds data (from 1999), covering over 7.3 million insured. To assess the gain in numerical efficiency, the computational time of the innovative approach has been compared with corresponding GAMs applied to simulated individual-level data. Furthermore, the probability of model failure was modeled via logistic regression. Applying the innovative method was reasonably fast (19 min). In contrast, regarding patient-level data, computational time increased disproportionately by sample size. Furthermore, using patient-level data was accompanied by a substantial risk of model failure (about 80 % for 6 million subjects). The gain in computational efficiency of the innovative COI method seems to be of practical relevance. Furthermore, it may yield more precise cost estimates.

Acceleration of an aldo-keto reductase by minimal loop engineering

Aldo-keto reductases tighten coenzyme binding by forming a hydrogen bond across the pyrophosphate group of NAD(P)(H). Mutation of the hydrogen bonding anchor Lys24 in Candida tenuis xylose reductase prevents fastening of the “safety belt” around NAD(H). The loosened NAD(H) binding leads to increased turnover numbers (k_cat) for reductions of bulky-bulky ketones at constant substrate and coenzyme affinities (i.e. K_{m Ketone}, K_{m NADH}).

EQUIPT: protocol of a comparative effectiveness research study evaluating cross-context transferability of economic evidence on tobacco control

INTRODUCTION

Tobacco smoking claims 700,000 lives every year in Europe and the cost of tobacco smoking in the EU is estimated between €98 and €130 billion annually; direct medical care costs and indirect costs such as workday losses each represent half of this amount. Policymakers all across Europe are in need of bespoke information on the economic and wider returns of investing in evidence-based tobacco control, including smoking cessation agendas. EQUIPT is designed to test the transferability of one such economic evidence base-the English Tobacco Return on Investment (ROI) tool-to other EU member states.

METHODS AND ANALYSIS

EQUIPT is a multicentre, interdisciplinary comparative effectiveness research study in public health. The Tobacco ROI tool already developed in England by the National Institute for Health and Care Excellence (NICE) will be adapted to meet the needs of European decision-makers, following transferability criteria. Stakeholders' needs and intention to use ROI tools in sample countries (Germany, Hungary, Spain and the Netherlands) will be analysed through interviews and surveys and complemented by secondary analysis of the contextual and other factors. Informed by this contextual analysis, the next phase will develop country-specific ROI tools in sample countries using a mix of economic modelling and Visual Basic programming. The results from the country-specific ROI models will then be compared to derive policy proposals that are transferable to other EU states, from which a centralised web tool will be developed. This will then be made available to stakeholders to cater for different decision-making contexts across Europe.

ETHICS AND DISSEMINATION

The Brunel University Ethics Committee and relevant authorities in each of the participating countries approved the protocol. EQUIPT has a dedicated work package on dissemination, focusing on stakeholders' communication needs. Results will be disseminated via peer-reviewed publications, e-learning resources and policy briefs.

The impact of preoperative patient characteristics on the cost-effectiveness of total hip replacement: a cohort study

Background

To facilitate the discussion on the increasing number of total hip replacements (THR) and their effectiveness, we apply a joint evaluation of hospital case costs and health outcomes at the patient level to enable comparative effectiveness research (CER) based on the preoperative health state.

Methods

In 2012, 292 patients from a German orthopedic hospital participated in health state evaluation before and 6 months after THR, where health-related quality of life (HRQoL) and disease specific pain and dysfunction were analyzed using EQ-5D and WOMAC scores. Costs were measured with a patient-based DRG costing scheme in a prospective observation of a cohort. Costs per quality-adjusted life year (QALY) were calculated based on the preoperative WOMAC score, as preoperative health states were found to be the best predictors of QALY gains in multivariate linear regressions.

Results

Mean inpatient costs of THR were 6,310 Euros for primary replacement and 7,730 Euros for inpatient lifetime costs including revisions. QALYs gained using the U.K. population preference-weighted index were 5.95. Lifetime costs per QALY were 1,300 Euros.

Conclusions

The WOMAC score and the EQ-5D score before operation were the most important predictors of QALY gains. The poorer the WOMAC score or the EQ-5D score before operation, the higher the patient benefit. Costs per QALY were far below common thresholds in all preoperative utility score groups and with all underlying calculation methodologies.

Comparison of pre- and post-operative health-related quality of life and length of stay after primary total hip replacement in matched English and German patient cohorts

PURPOSE

We compare pre- and post-operative health-related quality of life (HRQoL) and length of stay after total hip replacement (THR) in matched German and English patient cohorts to test for differences in admission thresholds, clinical effectiveness and resource utilisation between the healthcare systems.

METHODS

German data (n = 271) were collected in a large orthopaedic hospital in Munich, Germany; English data (n = 26,254) were collected as part of the national patient-reported outcome measures programme. HRQoL was measured using the EuroQoL-5D instrument. Propensity score matching was used to construct two patient cohorts that are comparable in terms of preoperative patient characteristics.

RESULTS

Before matching, patients in England showed lower preoperative EQ-5D scores (0.35 vs 0.52, p < 0.001) and experienced a larger improvement in HRQoL (0.43 vs 0.33, p < 0.001) than German patients. Patients in the German cohort were more likely to report no or only moderate problems with mobility and pain preoperatively than their English counterparts. After matching, improvements in HRQoL were comparable (0.32 vs 0.33, p = 0.638); post-operative scores were slightly higher in the German cohort (0.82 vs 0.85, p = 0.585). Length of stay was substantially lower in England than in Germany (4.5 vs 9.0 days, p < 0.001).

CONCLUSIONS

Our results highlight differences in preoperative health status between countries, which may arise due to different admission thresholds and access to surgery. In terms of quality of life, THR surgery is equally effective in both countries when performed on similar patients, but hospital stay is shorter in England.

The impact of preoperative patient characteristics on health states after total hip replacement and related satisfaction thresholds: a cohort study

BACKGROUND

The aim of the study was to analyze the effect of preoperative patient characteristics on health outcomes 6 months after total hip replacement (THR), to support patient's decision making in daily practice with predicted health states and satisfaction thresholds. By giving incremental effects for different patient subgroups, we support comparative effectiveness research (CER) on osteoarthritis interventions.

METHODS

In 2012, 321 patients participated in health state evaluation before and 6 months after THR. Health-related quality of life (HRQoL) was measured with the EQ-5D questionnaire. Hip-specific pain, function, and mobility were measured with the WOMAC in a prospective observation of a cohort. The predictive capability of preoperative patient characteristics - classified according to socio-demographic factors, medical factors, and health state variables - for changes in health outcomes is tested by correlation analysis and multivariate linear regressions. Related satisfaction thresholds were calculated with the patient acceptable symptom state (PASS) concept.

RESULTS

The mean WOMAC and EQ-5D scores before operation were 52 and 60 respectively (0 worst, 100 best). At the 6-month follow-up, scores improved by 35 and 19 units. On average, patients reported satisfaction with the operation if postoperative (change) WOMAC scores were higher than 85 (32) and postoperative (change) EQ-5D scores were higher than 79 (14).

CONCLUSIONS

Changes in WOMAC and EQ-5D scores can mainly be explained by preoperative scores. The lower the preoperative WOMAC or EQ-5D scores, the higher the change in the scores. Very good or very poor preoperative scores lower the probability of patient satisfaction with THR. Shared decision making using a personalized risk assessment approach provides predicted health states and satisfaction thresholds.

Transport as a sensitive indicator of quantum criticality

We consider bosonic transport through one-dimensional spin systems. Transport is induced by coupling the spin systems to bosonic reservoirs kept at different temperatures. In the limit of weak-coupling between spins and bosons we apply the quantum-optical master equation to calculate the energy transmitted from source to drain reservoirs. At large thermal bias, we find that the current for longitudinal transport becomes independent of the chain length and is also not drastically affected by the presence of disorder. In contrast, at small temperatures, the current scales inversely with the chain length and is further suppressed in the presence of disorder. We also find that the critical behaviour of the ground state is mapped to critical behaviour of the current--even in configurations with infinite thermal bias.

Hospital financing: calculating inpatient capital costs in Germany with a comparative view on operating costs and the English costing scheme

OBJECTIVES

The paper analyzes the German inpatient capital costing scheme by assessing its cost module calculation. The costing scheme represents the first separated national calculation of performance-oriented capital cost lump sums per DRG.

METHODS

The three steps in the costing scheme are reviewed and assessed: (1) accrual of capital costs; (2) cost-center and cost category accounting; (3) data processing for capital cost modules. The assessment of each step is based on its level of transparency and efficiency. A comparative view on operating costing and the English costing scheme is given.

RESULTS

Advantages of the scheme are low participation hurdles, low calculation effort for G-DRG calculation participants, highly differentiated cost-center/cost category separation, and advanced patient-based resource allocation. The exclusion of relevant capital costs, nontransparent resource allocation, and unclear capital cost modules, limit the managerial relevance and transparency of the capital costing scheme.

CONCLUSIONS

The scheme generates the technical premises for a change from dual financing by insurances (operating costs) and state (capital costs) to a single financing source. The new capital costing scheme will intensify the discussion on how to solve the current investment backlog in Germany and can assist regulators in other countries with the introduction of accurate capital costing.

Improving patient-level costing in the English and the German 'DRG' system

OBJECTIVES

The purpose of this paper is to develop ways to improve patient-level cost apportioning (PLCA) in the English and German inpatient 'DRG' cost accounting systems, to support regulators in improving costing schemes, and to give clinicians and hospital management sophisticated tools to measure and link their management.

METHODS

The paper analyzes and evaluates the PLCA step in the cost accounting schemes of both countries according to the impact on the key aspects of DRG introduction: transparency and efficiency. The goal is to generate a best available PLCA standard with enhanced accuracy and managerial relevance, the main requirements of cost accounting.

RESULTS

A best available PLCA standard in 'DRG' cost accounting uses: (1) the cost-matrix from the German system; (2) a third axis in this matrix, representing service-lines or clinical pathways; (3) a scoring system for key cost drivers with the long-term objective of time-driven activity-based costing and (4) a point of delivery separation.

CONCLUSION

Both systems have elements that the other system can learn from. By combining their strengths, regulators are supported in enhancing PLCA systems, improving the accuracy of national reimbursement and the managerial relevance of inpatient cost accounting systems, in order to reduce costs in health care.

Assessing DRG cost accounting with respect to resource allocation and tariff calculation: the case of Germany

The purpose of this paper is to analyze the German diagnosis related groups (G-DRG) cost accounting scheme by assessing its resource allocation at hospital level and its tariff calculation at national level. First, the paper reviews and assesses the three steps in the G-DRG resource allocation scheme at hospital level: (1) the groundwork; (2) cost-center accounting; and (3) patient-level costing. Second, the paper reviews and assesses the three steps in G-DRG national tariff calculation: (1) plausibility checks; (2) inlier calculation; and (3) the "one hospital" approach. The assessment is based on the two main goals of G-DRG introduction: improving transparency and efficiency. A further empirical assessment attests high costing quality. The G-DRG cost accounting scheme shows high system quality in resource allocation at hospital level, with limitations concerning a managerially relevant full cost approach and limitations in terms of advanced activity-based costing at patient-level. However, the scheme has serious flaws in national tariff calculation: inlier calculation is normative, and the "one hospital" model causes cost bias, adjustment and representativeness issues. The G-DRG system was designed for reimbursement calculation, but developed to a standard with strategic management implications, generalized by the idea of adapting a hospital's cost structures to DRG revenues. This combination causes problems in actual hospital financing, although resource allocation is advanced at hospital level.

Smoking and health-related quality of life in English general population: implications for economic evaluations

BACKGROUND

Little is known as to how health-related quality of life (HRQoL) when measured by generic instruments such as EQ-5D differ across smokers, ex-smokers and never-smokers in the general population; whether the overall pattern of this difference remain consistent in each domain of HRQoL; and what implications this variation, if any, would have for economic evaluations of tobacco control interventions.

METHODS

Using the 2006 round of Health Survey for England data (n = 13,241), this paper aims to examine the impact of smoking status on health-related quality of life in English population. Depending upon the nature of the EQ-5D data (i.e. tariff or domains), linear or logistic regression models were fitted to control for biology, clinical conditions, socio-economic background and lifestyle factors that an individual may have regardless of their smoking status. Age- and gender-specific predicted values according to smoking status are offered as the potential 'utility' values to be used in future economic evaluation models.

RESULTS

The observed difference of 0.1100 in EQ-5D scores between never-smokers (0.8839) and heavy-smokers (0.7739) reduced to 0.0516 after adjusting for biological, clinical, lifestyle and socioeconomic conditions. Heavy-smokers, when compared with never-smokers, were significantly more likely to report some/severe problems in all five domains--mobility (67%), self-care (70%), usual activity (42%), pain/discomfort (46%) and anxiety/depression (86%). 'Utility' values by age and gender for each category of smoking are provided to be used in the future economic evaluations.

CONCLUSION

Smoking is significantly and negatively associated with health-related quality of life in English general population and the magnitude of this association is determined by the number of cigarettes smoked. The varying degree of this association, captured through instruments such as EQ-5D, may need to be fed into the design of future economic evaluations where the intervention being evaluated affects (e.g. tobacco control) or is affected (e.g. treatment for lung cancer) by individual's (or patients') smoking status.

Evaluation of the EMIT Mycophenolic Acid Assay from Dade Behring

The Emit Mycophenolic Acid Assay, a new homogeneous enzyme immunoassay for the quantitative analysis of mycophenolic acid (MPA) in human plasma, was evaluated and compared to a high-performance liquid chromatography (HPLC) method. Coefficients of variation (CV) of the within-run imprecision (n = 10) varied from 2.5% to 4.4% and from 1.3% to 4.9% for the Emit and the HPLC, respectively. The CV's of between-day imprecision (n = 10) ranged from 7.9% to 10.8% for the Emit and from 4.7% to 12.1% for the HPLC. Mean recoveries were 95.6% and 100.1% for Emit and HPLC, respectively. Serial dilution of a patient pool demonstrated a linear relationship between expected (x) and measured (y) concentrations: Emit, y = 0.998x + 0.086; HPLC, y = 1.006x - 0.016. The detection limit and the lower limit of quantification were 0.087 mg/L and 0.20 mg/L for Emit. The detection limit for HPLC was 0.08 mg/L using a signal-to-noise ratio of three. Sample stability under various storage conditions was satisfactory, although storage at -20 degrees C is recommended for storage longer than one day. No cross-reactivity from the major metabolite mycophenolic acid glucuronide (MPAG) was found. A correlation study on 261 patient samples yielded the following regression equation (bivariate Deming procedure): Emit = 1.012HPLC + 0.244, r = 0.970.

Noninvasive monitoring using serum amyloid A and serum neopterin in cardiac transplantation

The monitoring of allograft function for cardiac transplant patients still relies on endomyocardial routine biopsies. We investigated the diagnostic value of noninvasive monitoring using the parameters serum amyloid A protein and serum neopterin. The circulating levels of the acute phase reactant, amyloid A protein, and the macrophage product, neopterin, were measured serially in 13 patients after cardiac transplantation. The mean period of observation was 240 days. Nine acute cardiac allograft rejections, five cases of viral infection and eight cases of bacterial infection occurred. The levels of serum amyloid A protein and serum neopterin remained low (x = 6.0 mg/dL and 12.6 nmol/L, respectively) during the periods of stable graft function. In contrast, both parameters were significantly elevated (p < 0.01) during the rejection episodes (x = 12.7 mg/dL and 38.0 nmol/L for serum amyloid A protein and serum neopterin, respectively). For a reliable differentiation between rejection and stable graft function, serum amyloid A protein had a diagnostic accuracy of 84% (with a cut-off level of 10 mg/dL) and serum neopterin had one of 75% (with a cut-off level of 23 nmol/L). However, significant increases in the circulating levels of serum amyloid A protein and serum neopterin were also observed during bacterial (x = 14.9 and 88 nmol/L, respectively) and viral (x = 6.2 mg/dL and 44 nmol/L, respectively) infections. The detection of immunological complications after cardiac transplantation using serial measurements of serum amyloid A protein and serum neopterin is possible. These parameters can be used to help in judging both the need and the optimal timing for the otherwise frequent endomyocardial biopsies.

Mycophenolic acid monitoring in HTX patients: a preliminary report

Mycophenolic acid (MPA) is a new immunosuppressive drug used in clinical trials in combination with cyclosporine A (CsA) and prednisolone. Its immunosuppressive mechanism consists in a non-competitive inhibition of the inosine monophosphate (IMP) dehydrogenase which is the key enzyme in the conversion of inosine monophosphate to guanosine monophosphate. Depletion of the guanine nucleotide pool impairs DNA synthesis and thus inhibits the cell cycle progression of T- and B-lymphocytes. For monitoring of MPA and its metabolite mycophenolic acid glucuronide (MPAG), a high performance liquid chromatography (HPLC) method, and for MPA an EMIT-immunoassay, were established. MPA HPLC and EMIT exhibit a linearity up to 10.00 mumol/l (3.20 micrograms/ml) and 46.95 mumol/l (15.00 micrograms/ml) respectively. Coefficients of variation for intra /inter-assay bias were 5.3/14.1 per cent for HPLC and 4.8/12.3 percent for the EMIT assay. The correlation between both methods was: HPLC = 0.82 EMIT -1.85 (r = 0.955); limits of agreement between the methods were 13.6 and -5.12 mumol/l. In 8 stable heart transplant recipients treated with 2 g mofetil/day, mean and median steady-state MPA concentrations for HPLC and EMIT were 6.86 mumol/l (2.19 micrograms/ml), 4.77 mumol/l (1.52 micrograms/ml) and 10.88 mumol/l (3.48 micrograms/ml), 7.42 mumol/l (2.37 micrograms/ml) respectively, during a period of 3 months. Mean and median MPAG concentrations were 141.21 mumol/l (61.40 micrograms/ml) and 100.70 mumol/l (43.78 micrograms/ml) respectively.

Clinical usefulness of percentage of free serum prostate specific antigen

Serum concentrations of total and free prostate specific antigen were measured retrospectively in 268 patients, in order to test the usefulness of percentage of free prostate specific antigen in distinguishing between cancer and benign hyperplasia of the prostate and to improve the specificity of cancer screening. Four groups were investigated: 94 urologic patients without prostate disease (controls), 98 patients with a histologically confirmed benign hyperplasia, 76 with histologically established prostatic adenocarcinoma, 18 of them after radical prostatectomy. Total and free prostate specific antigen concentrations were measured in frozen serum, in a retrospective mode, by using an equimolar monoclonal antibody immunoassay. Median percentage of free prostate specific antigen was 20.48% in controls, 17.75% in patients with hyperplasia, 10.52% in patients with cancer and 33.03% in patients after prostatectomy. Median percentage of free prostate specific antigen was significantly lower in men with cancer than in patients with benign hyperplasia (P < 0.0001). The percentage of free prostate specific antigen increased the specificity of cancer screening: a cut-off of 23.6% detected at least 90% of cancers and would have eliminated 34.7% of biopsies in benign hyperplasias. A prospective study is ongoing to confirm these results.

Tissue polypeptide specific antigen for the detection of lymphoproliferative diseases induced by cyclosporin

AIM

To evaluate the efficacy of tissue polypeptide specific (TPS) antigen for the early detection of cyclosporin A (CyA) induced post-transplant lymphoproliferative diseases.

METHODS

Serum concentrations of TPS antigen were analysed using a monoclonal enzyme immunoassay and whole blood CyA concentrations were measured using high pressure liquid chromatography. Infection with Epstein-Barr virus and cytomegalovirus was detected by determining levels of IgM and IgG antibodies directed against viral capsid antigen (VCA). Immunohistochemistry and analysis of clonality were carried out on formalin fixed, paraffin wax embedded tissue.

RESULTS

The mean serum concentration of TPS antigen in the eight transplant recipients investigated was 60 U/l during periods without complication (control), 101 U/l during infection, 166 U/l when the diagnosis of a lymphoma was confirmed, and 172 U/l when lymphoma and infection coincided. Increased TPS antigen concentrations were detected in six patients one month before detection of malignancy. After reduction of immunosuppression and the start of tumour regression, TPS antigen concentrations decreased. TPS antigen concentrations increased in the one patient who experienced a recurrence.

CONCLUSIONS

Continuous monitoring of TPS antigen concentrations leads to the early discovery of CyA induced lymphoproliferative disease.

Tissue polypeptide specific antigen, neopterin, and CRP for monitoring heart transplant recipients

OBJECTIVES

The aim of our study was to investigate the usefulness of tissue polypeptide specific antigen, an established tumor marker detecting proliferation of cells, for monitoring heart transplant recipients in order to detect infection and rejection early.

METHODS

Tissue polypeptide specific antigen serum levels were compared with neopterin and C-reactive protein serum concentrations.

RESULTS

When infections occurred, tissue polypeptide specific antigen serum concentrations were increased approximately five times (mean: 214 U/L, SD 145), while in instances of acute rejection crises, they were increased two times (mean: 76 U/L, SD 16 in comparison with the values during uncomplicated postoperative courses (mean: 45 U/L, SD 26).

CONCLUSIONS

Tissue polypeptide specific antigen was the only investigated analyte that showed significant diagnostic validities when infections were compared with rejections. The discrimination between an uncomplicated postoperative course and a rejection or infection episode was only possible with a combination of the three analytes.