The effects of industry funding and positive outcomes in the interpretation of clinical trial results: a randomized trial among Dutch psychiatrists.

BACKGROUND: Most studies are inclined to report positive rather than negative or inconclusive results. It is currently unknown how clinicians appraise the results of a randomized clinical trial. For example, how does the study funding source influence the appraisal of an RCT, and do positive findings influence perceived credibility and clinical relevance? This study investigates whether psychiatrists' appraisal of a scientific abstract is influenced by industry funding disclosures and a positive outcome. METHODS: Dutch psychiatrists were randomized to evaluate a scientific abstract describing a fictitious RCT for a novel antipsychotic drug. Four different abstracts were created reporting either absence or presence of industry funding disclosure as well as a positive or a negative outcome. Primary outcomes were the perceived credibility and clinical relevance of the study results (10-point Likert scale). Secondary outcomes were the assessment of methodological quality and interest in reading the full article. RESULTS: Three hundred ninety-five psychiatrists completed the survey (completion rate 45%). Industry funding disclosure was found not to influence perceived credibility (Mean Difference MD 0.12; 95% CI - 0.28 to 0.47, p?) nor interpretation of its clinical relevance (MD 0.14; 95% CI - 0.54 to 0.27, p?). A negative outcome was perceived as more credible than a positive outcome (MD 0.81 points; 95% Confidence Interval (CI) 0.43 to 1.18, p?), but did not affect clinical relevance scores (MD -0.14; 95% CI - 0.54 to 0.27). CONCLUSIONS: In this study, industry funding disclosure was not associated with the perceived credibility nor judgement of clinical relevance of a fictional RCT by psychiatrists. Positive study outcomes were found to be less credible compared to negative outcomes, but industry funding had no significant effects. Psychiatrists may underestimate the influence of funding sources on research results. The fact that physicians indicated negative outcomes to be more credible may point to more awareness of existing publication bias in the scientific literature.

Inter-rater agreement and reliability of the COSMIN (COnsensus-based Standards for the selection of health status Measurement Instruments) checklist.

BACKGROUND: The COSMIN checklist is a tool for evaluating the methodological quality of studies on measurement properties of health-related patient-reported outcomes. The aim of this study is to determine the inter-rater agreement and reliability of each item score of the COSMIN checklist (n = 114). METHODS: 75 articles evaluating measurement properties were randomly selected from the bibliographic database compiled by the Patient-Reported Outcome Measurement Group, Oxford, UK. Raters were asked to assess the methodological quality of three articles, using the COSMIN checklist. In a one-way design, percentage agreement and intraclass kappa coefficients or quadratic-weighted kappa coefficients were calculated for each item. RESULTS: 88 raters participated. Of the 75 selected articles, 26 articles were rated by four to six participants, and 49 by two or three participants. Overall, percentage agreement was appropriate (68% was above 80% agreement), and the kappa coefficients for the COSMIN items were low (61% was below 0.40, 6% was above 0.75). Reasons for low inter-rater agreement were need for subjective judgement, and accustom to different standards, terminology and definitions. CONCLUSIONS: Results indicated that raters often choose the same response option, but that it is difficult on item level to distinguish between articles. When using the COSMIN checklist in a systematic review, we recommend getting some training and experience, completing it by two independent raters, and reaching consensus on one final rating. Instructions for using the checklist are improved.

The COSMIN checklist for evaluating the methodological quality of studies on measurement properties: a clarification of its content.

BACKGROUND: The COSMIN checklist (COnsensus-based Standards for the selection of health status Measurement INstruments) was developed in an international Delphi study to evaluate the methodological quality of studies on measurement properties of health-related patient reported outcomes (HR-PROs). In this paper, we explain our choices for the design requirements and preferred statistical methods for which no evidence is available in the literature or on which the Delphi panel members had substantial discussion. METHODS: The issues described in this paper are a reflection of the Delphi process in which 43 panel members participated. RESULTS: The topics discussed are internal consistency (relevance for reflective and formative models, and distinction with unidimensionality), content validity (judging relevance and comprehensiveness), hypotheses testing as an aspect of construct validity (specificity of hypotheses), criterion validity (relevance for PROs), and responsiveness (concept and relation to validity, and (in) appropriate measures). CONCLUSIONS: We expect that this paper will contribute to a better understanding of the rationale behind the items, thereby enhancing the acceptance and use of the COSMIN checklist.

The COSMIN checklist for assessing the methodological quality of studies on measurement properties of health status measurement instruments: an international Delphi study.

BACKGROUND: Aim of the COSMIN study (COnsensus-based Standards for the selection of health status Measurement INstruments) was to develop a consensus-based checklist to evaluate the methodological quality of studies on measurement properties. We present the COSMIN checklist and the agreement of the panel on the items of the checklist. METHODS: A four-round Delphi study was performed with international experts (psychologists, epidemiologists, statisticians and clinicians). Of the 91 invited experts, 57 agreed to participate (63%). Panel members were asked to rate their (dis)agreement with each proposal on a five-point scale. Consensus was considered to be reached when at least 67% of the panel members indicated 'agree' or 'strongly agree'. RESULTS: Consensus was reached on the inclusion of the following measurement properties: internal consistency, reliability, measurement error, content validity (including face validity), construct validity (including structural validity, hypotheses testing and cross-cultural validity), criterion validity, responsiveness, and interpretability. The latter was not considered a measurement property. The panel also reached consensus on how these properties should be assessed. CONCLUSIONS: The resulting COSMIN checklist could be useful when selecting a measurement instrument, peer-reviewing a manuscript, designing or reporting a study on measurement properties, or for educational purposes.

Assessing the impact of health technology assessment in The Netherlands.

OBJECTIVES: Investments in health research should lead to improvements in health and health care. This is also the remit of the main HTA program in the Netherlands. The aims of this study were to assess whether the results of this program have led to such improvements and to analyze how best to assess the impact from health research. METHODS: We assessed the impact of individual HTA projects by adapting the "payback framework" developed in the United Kingdom. We conducted dossier reviews and sent a survey to principal investigators of forty-three projects awarded between 2000 and 2003. We then provided an overview of documented output and outcome that was assessed by ten HTA experts using a scoring method. Finally, we conducted five case studies using information from additional dossier review and semistructured key informant interviews. RESULTS: The findings confirm that the payback framework is a useful approach to assess the impact of HTA projects. We identified over 101 peer reviewed papers, more than twenty-five PhDs, citations of research in guidelines (six projects), and implementation of new treatment strategies (eleven projects). The case studies provided greater depth and understanding about the levels of impact that arise and why and how they have been achieved. CONCLUSIONS: It is generally too early to determine whether the HTA program led to actual changes in healthcare policy and practice. However, the results can be used as a baseline measurement for future evaluation and can help funding organizations or HTA agencies consider how to assess impact, possibly routinely. This, in turn, could help inform research strategies and justify expenditure for health research.

Cost-effectiveness of usual general practitioner care with or without antidepressant medication for patients with minor or mild-major depression.

BACKGROUND: Minor depression is common in primary care and associated with increased health care costs. Many mildly depressed patients are prescribed antidepressants, although there is insufficient information on the cost-effectiveness of antidepressants for these patients. The objective of this study was to evaluate whether usual care without antidepressants is equivalent to (i.e. as effective as and as expensive as) usual care with antidepressants in patients with minor or mild-major depression. METHODS: Severity of depression was measured using the Montgomery Asberg Depression Rating Scale (MADRS) and quality-adjusted life-years (QALYs) using the EuroQol. Resource use was measured from a societal perspective using cost diaries. Bootstrapping was used to analyze the cost-effectiveness data. RESULTS: Equivalence could not be shown for improvement in MADRS score or QALYs gained at 52 weeks. The mean (95% CI) difference in total costs between usual care without antidepressants and usual care with antidepressants was -euro751 (-3601; 1522). Using an equivalence margin of euro500 equivalence in costs could not be shown. In the cost-effectiveness analyses equivalence also could not be shown. LIMITATIONS: This study was underpowered for economic outcomes. Another limitation was the loss-to-follow-up. CONCLUSIONS: Although equivalence could not be shown in the costs and cost-effectiveness analyses, 95% confidence intervals also did not show that usual care without antidepressants was vastly superior or inferior to usual care with antidepressants. Therefore, we recommend general practitioners to show restraint when prescribing antidepressants to mildly depressed patients.

Low back pain in general practice: cost-effectiveness of a minimal psychosocial intervention versus usual care.

An intervention that can prevent low back pain (LBP) becoming chronic, may not only prevent great discomfort for patients, but also save substantial costs for the society. Psychosocial factors appear to be of importance in the transition of acute to chronic LBP. The aim of this study was to compare the cost-effectiveness of an intervention aimed at psychosocial factors to usual care in patients with (sub)acute LBP. The study design was an economic evaluation alongside a cluster-randomized controlled trial, conducted from a societal perspective with a follow-up of 1 year. Sixty general practitioners in 41 general practices recruited 314 patients with non-specific LBP of less than 12 weeks' duration. General practitioners in the minimal intervention strategy (MIS) group explored and discussed psychosocial prognostic factors. Usual care (UC) was not protocolized. Clinical outcomes were functional disability (Roland-Morris Disability Questionnaire), perceived recovery and health-related quality of life (EuroQol). Cost data consisted of direct and indirect costs and were measured by patient cost diaries and general practitioner registration forms. Complete cost data were available for 80% of the patients. Differences in clinical outcomes between both the groups were small and not statistically significant. Differences in cost data were in favor of MIS. However, the complete case analysis and the sensitivity analyses with imputed cost data were inconsistent with regard to the statistical significance of this difference in cost data. This study presents conflicting points of view regarding the cost-effectiveness of MIS. We conclude that (Dutch) general practitioners, as yet, should not replace their usual care by this new intervention.

Prevention of fall incidents in patients with a high risk of falling: design of a randomised controlled trial with an economic evaluation of the effect of multidisciplinary transmural care.

BACKGROUND: Annually, about 30% of the persons of 65 years and older falls at least once and 15% falls at least twice. Falls often result in serious injuries, such as fractures. Therefore, the prevention of accidental falls is necessary. The aim is to describe the design of a study that evaluates the efficacy and cost-effectiveness of a multidisciplinary assessment and treatment of multiple fall risk factors in independently living older persons with a high risk of falling. METHODS/DESIGN: The study is designed as a randomised controlled trial (RCT) with an economic evaluation. Independently living persons of 65 years and older who recently experienced a fall are interviewed in their homes and screened for risk of recurrent falling using a validated fall risk profile. Persons at low risk of recurrent falling are excluded from the RCT. Persons who have a high risk of recurrent falling are blindly randomised into an intervention (n = 100) or usual care (n = 100) group. The intervention consists of a multidisciplinary assessment and treatment of multifactorial fall risk factors. The transmural multidisciplinary approach entails close cooperation between geriatrician, primary care physician, physical therapist and occupational therapist and can be extended with other specialists if relevant. A fall calendar is used to record falls during one year of follow-up. Primary outcomes are time to first and second falls. Three, six and twelve months after the home visit, questionnaires for economic evaluation are completed. After one year, during a second home visit, the secondary outcome measures are reassessed and the adherence to the interventions is evaluated. Data will be analysed according to the intention-to-treat principle and also an on-treatment analysis will be performed. DISCUSSION: Strengths of this study are the selection of persons at high risk of recurrent falling followed by a multidisciplinary intervention, its transmural character and the evaluation of adherence. If proven effective, implementation of our multidisciplinary assessment followed by treatment of fall risk factors will reduce the incidence of falls. TRIAL REGISTRATION: Current Controlled Trials ISRCTN11546541.

Cost effectiveness of a pharmacy-based coaching programme to improve adherence to antidepressants.

INTRODUCTION: The efficacy of antidepressants in the treatment of depression has been convincingly demonstrated in randomised trials. However, non-adherence to antidepressant treatment is common. OBJECTIVE: To evaluate, from a societal perspective, the cost effectiveness of a pharmacy-based intervention to improve adherence to antidepressant therapy in adult patients receiving treatment in primary care. METHODS: An economic evaluation was performed alongside a 6-month randomised controlled trial in The Netherlands. Patients who came to 19 pharmacies with a new prescription for a non-tricyclic antidepressant, i.e. those who had not received any prescription for an antidepressant in the past 6 months, were invited to participate. They were then randomly allocated to education and coaching by the pharmacist or to usual care. The coaching programme consisted of three contacts with the pharmacist, with a mean duration of between 13 and 20 minutes, and a take-home video reviewing important facts on depression and antidepressant treatment. The clinical outcome measures were adherence to antidepressant treatment measured using an electronic pill container (eDEM) and improvement in depressive symptoms measured using the Hopkins Symptom Checklist (SCL). Resource use was measured by means of questionnaires. The uncertainty around differences in costs and cost effectiveness between the treatment groups was evaluated using bootstrapping. RESULTS: Seventy patients were randomised to the intervention group and 81 to the usual care group; of these, 40 in the intervention group and 48 in the control group completed all of the follow-up questionnaires. There were no significant differences in adherence, improvements in the SCL depression mean item score and costs over 6 months between the two treatment groups. Mean total costs (2002 values) were 3275 euros in the intervention group and 2961 euros in the control group (mean difference 315 euros; 95% CI -1922, 2416). The incremental cost-effectiveness ratio associated with the pharmacist intervention was 149 euros per 1% improvement in adherence and 2550 euros per point improvement in the SCL depression mean item score. Cost-effectiveness planes and acceptability curves indicated that the pharmacist intervention was not likely to be cost effective compared with usual care. CONCLUSION: In patients starting treatment with antidepressants, there were no significant differences in adherence, severity of depression, costs and cost effectiveness between patients receiving coaching by a pharmacist and patients receiving usual care after 6 months. Considering the resources needed to implement an intervention like this in clinical practice, based on these results, the continuation of usual care is recommended.

Minimally important change determined by a visual method integrating an anchor-based and a distribution-based approach.

BACKGROUND: Minimally important changes (MIC) in scores help interpret results from health status instruments. Various distribution-based and anchor-based approaches have been proposed to assess MIC. OBJECTIVES: To describe and apply a visual method, called the anchor-based MIC distribution method, which integrates both approaches. METHOD: Using an anchor, patients are categorized as persons with an important improvement, an important deterioration, or without important change. For these three groups the distribution of the change scores on the health status instrument are depicted in a graph. We present two cut-off points for an MIC: the ROC cut-off point and the 95% limit cut-off point. RESULTS: We illustrate our anchor-based MIC distribution method determining the MIC for the Pain Intensity Numerical Rating Scale in patients with low back pain, using two conceivable definitions of minimal important change on the anchor. The graph shows the distribution of the scores of the health status instrument for the relevant categories on the anchor, and also the consequences of choosing the ROC cut-off point or the 95% limit cut-off point. DISCUSSION: The anchor-based MIC distribution method provides a general framework, applicable to all kind of anchors. This method forces researchers to choose and justify their choice of an appropriate anchor and to define minimal importance on that anchor. The MIC is not an invariable characteristic of a measurement instrument, but may depend, among other things, on the perspective from which minimal importance is considered and the baseline values on the measurement instrument under study. A balance needs to be struck between the practicality of a single MIC value and the validity of a range of MIC values.

Quality criteria were proposed for measurement properties of health status questionnaires.

OBJECTIVES: Recently, an increasing number of systematic reviews have been published in which the measurement properties of health status questionnaires are compared. For a meaningful comparison, quality criteria for measurement properties are needed. Our aim was to develop quality criteria for design, methods, and outcomes of studies on the development and evaluation of health status questionnaires. STUDY DESIGN AND SETTING: Quality criteria for content validity, internal consistency, criterion validity, construct validity, reproducibility, longitudinal validity, responsiveness, floor and ceiling effects, and interpretability were derived from existing guidelines and consensus within our research group. RESULTS: For each measurement property a criterion was defined for a positive, negative, or indeterminate rating, depending on the design, methods, and outcomes of the validation study. CONCLUSION: Our criteria make a substantial contribution toward defining explicit quality criteria for measurement properties of health status questionnaires. Our criteria can be used in systematic reviews of health status questionnaires, to detect shortcomings and gaps in knowledge of measurement properties, and to design validation studies. The future challenge will be to refine and complete the criteria and to reach broad consensus, especially on quality criteria for good measurement properties.

Costs of shoulder pain in primary care consulters: a prospective cohort study in The Netherlands.

BACKGROUND: Shoulder pain is common in primary care, and has an unfavourable outcome in many patients. Information on the costs associated with health care use and loss of productivity in patients with shoulder pain is very scarce. The objective of this study was to determine shoulder pain related costs during the 6 months after first consultation in general practice METHODS: A prospective cohort study consisting of 587 patients with a new episode of shoulder pain was conducted with a follow-up period of 6 months. Data on costs were collected by means of a cost diary during 6 months. RESULTS: 84% of the patients completed all cost diaries. The mean consumption of direct health care and non-health related care was low. During 6 months after first consultation for shoulder pain, the mean total costs a patient generated were 689 euro. Almost 50% of this total concerned indirect costs, caused by sick leave from paid work. A small proportion (12%) of the population generated 74% of the total costs. CONCLUSION: The total costs in the 6 months after first consultation for shoulder pain in primary care, mostly generated by a small part of the population, are not alarmingly high.

Surgery is more cost-effective than splinting for carpal tunnel syndrome in the Netherlands: results of an economic evaluation alongside a randomized controlled trial.

BACKGROUND: Carpal tunnel syndrome (CTS) is a common disorder, often treated with surgery or wrist splinting. The objective of this economic evaluation alongside a randomized trial was to evaluate the cost-effectiveness of splinting and surgery for patients with CTS. METHODS: Patients at 13 neurological outpatient clinics with clinically and electrophysiologically confirmed idiopathic CTS were randomly allocated to splinting (n = 89) or surgery (n = 87). Clinical outcome measures included number of nights waking up due to symptoms, general improvement, severity of the main complaint, paraesthesia at night and during the day, and utility. The economic evaluation was performed from a societal perspective and involved all relevant costs. RESULTS: There were no differences in costs. The mean total costs per patient were in the surgery group EURO 2,126 compared to EURO 2,111 in the splint group. After 12 months, the success rate in the surgery group (92%) was significantly higher than in the splint group (72%). The acceptability curve showed that at a relatively low ceiling ratio of EURO 2,500 per patient there is a 90% probability that surgery is cost-effective. CONCLUSION: In the Netherlands, surgery is more cost-effective compared with splinting, and recommended as the preferred method of treatment for patients with CTS.

Comparison of the effectiveness of a behavioural graded activity program and manual therapy in patients with sub-acute neck pain: design of a randomized clinical trial.

The objective is to present the design of a randomized clinical trial (RCT) on the effectiveness and cost effectiveness of a behavioural graded activity programme compared with manual therapy in patients with sub-acute neck pain. Sub-acute is defined as pain existing for 4-12 weeks. The behavioural graded activity programme is a time-contingent increase in activities from baseline towards pre-determined goals. Manual therapy consists mainly of specific spinal mobilization techniques and exercises. The primary outcomes are global perceived effect and functional status. Secondary outcomes are kinesiophobia, distress, coping, depression and somatization. The intensity and persistence of the pain and its interference with activities are also assessed. Direct and indirect costs are measured by means of cost diaries. Measurements take place at baseline and 6 and 12 weeks after randomization. To assess the long-term effect, measurements will also take place after 6 and 12 months. Finally some challenges are discussed concerning the use of a behavioural graded activity programme, manual therapy and outcomes.

Health-related and overall quality of life of patients with chronic hip and knee complaints in general practice.

BACKGROUND: Information about quality of life of patients with chronic hip or knee complaints in general practice is scarce. This study describes the health-related and overall quality of life (HRQL) of these complaints. METHODS: Data were obtained from a cohort study in general practice. HRQL at three months follow-up was analysed. HRQL was measured as: symptoms, physical, psychological and social functioning, and general health perceptions, using the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) and the MOS 36-item short-form-health survey (SF-36). Overall quality of life was measured using a 5-point rating scale. RESULTS: The results show that patients with chronic hip or knee complaints have a substantial lower HRQL compared to patients who had recovered from baseline hip or knee complaints. The largest effect was found on symptoms and physical functioning: up to 2.9 standard deviations below patients who had recovered from baseline hip or knee complaints. Scores of patients with both chronic hip and knee complaints were significantly worse than scores of patients with only knee complaints on most subscales. CONCLUSION: In patients with chronic hip or knee complaints the worst scores were seen on scales that measure symptoms and physical functioning, but still a substantially lower score was obtained for overall quality of life. Quality of life was poorer for patients with both chronic hip and knee complaints compared to those with chronic hip or knee complaints only.

Impairment measures in rheumatic disorders for rehabilitation medicine and allied health care: a systematic review.

UNLABELLED: The objective of this study is to provide a critical overview of available instruments to assess impairments in patients with rheumatic disorders, and to recommend reliable and valid instruments for use in allied health care and rehabilitation medicine. A computer-aided literature search (1982-2004) in several databases was performed to identify studies focusing on the clinimetric properties of instruments designed to assess impairments in function in patients with rheumatic disorders. Data on intra-rater reliability, inter-rater reliability and construct validity were extracted in a standardized way. Explicit criteria were applied for reliability and validity. RESULTS: The search identified a total of 49 instruments to assess impairments in functions in patients with rheumatic disorders; 19 met the criteria for reliability, 22 met the criteria for validity, and 11 out of the 49 appeared to meet the criteria for both reliability and validity. In summary, evidence of both reliability and validity was only found for 11 out of 49 instruments for the assessment of impairments in patients with rheumatic disorders. Only a limited number of the identified instruments for the assessment of impairments is both reliable and valid. Allied health care professionals should be cautious in the selection of measurement instruments to assess their patients.

Assessing pain in patients with severe cerebral palsy: development, reliability, and validity of a pain assessment instrument for cerebral palsy.

OBJECTIVES: To develop the Pain Assessment Instrument for Cerebral Palsy (PAICP) and to study its test-retest reproducibility and construct validity. DESIGN: Cross-sectional validation study. SETTING: Homes for severely handicapped. PARTICIPANTS: A total of 164 adults with severe cerebral palsy (CP), caregivers, and physiotherapists, and 9 healthy children. INTERVENTIONS: The PAICP contains drawings of situations, some situations of which usually produce pain. Patients rate the pain associated with each activity using a Faces Pain Scale. Reproducibility and construct validity was assessed in a pilot study with CP patients and healthy children. Construct validity and agreement between the pain scores of the patients and proxies was assessed in 160 patients with severe CP. MAIN OUTCOME MEASURE: Pain score on the PAICP. RESULTS: The measure showed adequate test-retest reproducibility. A significant difference was found between the mean scores for "painful" and "not painful" situations. We also found moderate agreement between the scores of the patients and proxies for daily activities but only for those activities in which the proxies were personally involved. CONCLUSIONS: The PAICP has adequate test-retest reproducibility and construct validity. It provides an indication of the pain experienced by patients in situations in which proxies are not personally involved and may also be more valid than proxy measures for other situations.

Cost-effectiveness of hip protectors in frail institutionalized elderly.

A randomized controlled trial was performed to examine the cost-effectiveness of external hip protectors in the prevention of hip fractures. Since the hip protectors were not effective in preventing hip fractures in our study, the main objective became to examine whether the use of hip protectors results in lower average costs per participant in the hip protector group as compared with the control group. In addition, the average costs of a hip fracture and subsequent rehabilitation in frail, institutionalized elderly were calculated. Residents from apartment houses for the elderly, homes for the elderly and nursing homes with a high risk for hip fractures were randomized to the hip protector group (n=276) or control group (n=285). Costs were calculated for the hip fracture and subsequent rehabilitation until 1 year after the fracture. Six months after each hip fracture, a nurse was interviewed and after 12 months, a questionnaire was sent to the general practitioner or nursing home physician to determine the utilization of health care resources. Differences in costs between the groups were analyzed using non-parametric bootstrapping. Eighteen hip fractures occurred in the intervention group and 20 hip fractures (in 19 persons) in the control group (log rank P-value=0.86). The average costs per participant, including the costs of the intervention, were Euro 913 in the intervention group and Euro 502 in the control group (cost difference of Euro -411; 95% confidence interval: -723; 57). The average costs of a hip fracture and subsequent rehabilitation were Euro 8100 (95% CI: 6716-10,010). The use of hip protectors was not associated with lower costs. In addition, the average costs of a hip fracture and subsequent rehabilitation in the first year after the fracture were estimated at Euro 8100 in institutionalized elderly.

Overestimation of complication rates in evaluations of Chlamydia trachomatis screening programmes--implications for cost-effectiveness analyses.

BACKGROUND: Cost-effectiveness analyses of screening programmes for asymptomatic Chlamydia trachomatis infection suggest that screening at low prevalences in the population is cost-effective. However, the decision models in these studies are based on assumptions about the risk of complications, which are derived from the literature. Incorrect assumptions may lead to under- or overestimation of the effectiveness of screening. The first objective of this paper is to evaluate the assumptions about the probability of complications after an asymptomatic C. trachomatis infection. The second objective is to calculate alternative rates by using available data on the incidence of complications. METHODS: We identified cost-effectiveness studies via Medline, and evaluated these for the evidence for the quoted probabilities. In addition, the probability of complications was calculated for Amsterdam from available registration data. RESULTS: In the three studies that were identified, the assumptions for the rates of pelvic inflammatory disease (PID) (clinical and subclinical) after C. trachomatis infection varied from 15% to 80%, and for ectopic pregnancy, tubal factor infertility, and chronic pelvic pain after PID from 5-25%, 10-20%, and 18-30%, respectively. The assumptions were based on data from high-risk populations, case-control data, and data not accounting for misdiagnoses. Using data obtained from local registrations, we estimated the probability of a clinical PID (0.43%), ectopic pregnancy (0.07%), and tubal factor infertility (0.02%) for women with a current infection. These estimates were consistently lower than the estimates based on the literature. CONCLUSIONS: We argue that an overestimation of the current complication rates is likely. The effect of overestimation is potentially the greatest in populations with a low prevalence, since the currently assumed cost savings associated with screening may disappear when using more realistic estimates for complications.