[Decision-making concerning unintended pregnancies: experiences of women and men, and insights from healthcare providers]. / Besluitvorming bij onbedoelde zwangerschappen.

OBJECTIVE: To gain insight into experiences of women and men who have experienced an unintended pregnancy, along with the perspectives of healthcare providers offering decision-making counseling/consultations concerning an unintended pregnancy or abortion. DESIGN: Semi-structured interviews and focus groups. METHODS: Twenty-five interviews were held with women and men whom experienced an unintended pregnancy, while nineteen healthcare providers participated in four focus groups (May-July 2021). RESULTS: In addition to partners or other family members, healthcare providers also play a significant role in supporting decision-making. Awareness of decision-making counseling was limited among interviewees, a view shared by the participating providers. Both groups highlighted deficiencies in follow-up care post-abortion or unintended pregnancy, as well as the perceived taboo surrounding unintended pregnancies and abortion. CONCLUSION: Decision-making counseling deserves more awareness among the public and healthcare providers. There is also room for improvement regarding follow-up care. Sustained attention to unintended pregnancies and abortions is necessary to reduce the prevailing taboo.

Costs of a clinical pathway with point-of-care testing during influenza epidemic in a Dutch hospital.

Our study aim was to determine how a new clinical pathway, including PCR-based influenza point-of-care test (POCT), influences the hospitalisation costs of patients suspected of influenza presenting at the emergency department of a Dutch hospital during two consecutive influenza epidemics (2016-2017 and 2017-2018). Compared to mean costs per patient of €3661 in 2016-2017, the implementation of this new clinical pathway with influenza POCT in 2017 was associated with mean costs per influenza-positive patient of €2495 in 2017-2018 (P = .3). Our study suggests favourable economic results regarding a new clinical pathway with influenza POCT, reflecting a more efficient care of patients suspected of influenza presenting at the emergency department.

Trading patients' choice in providers for quality of maternity care? A discrete choice experiment amongst pregnant women.

BACKGROUND: The introduction of bundled payment for maternity care, aimed at improving the quality of maternity care, may affect pregnant women's choice in providers of maternity care. This paper describes a Dutch study which examined pregnant women's preferences when choosing a maternity care provider. The study focused on factors that enhance the quality of maternity care versus (restricted) provider choice. METHODS: A discrete choice experiment was conducted amongst 611 pregnant women living in the Netherlands using an online questionnaire. The data were analysed with Latent Class Analyses. The outcome measure consisted of stated preferences in the discrete choice experiment. Included factors were: information exchange by care providers through electronic medical records, information provided by midwife, information provided by friends, freedom to choose maternity care provider and travel distance. RESULTS: Four different preference structures were found. In two of those structures, respondents found aspects of the maternity care related to quality of care more important than being able to choose a provider (provider choice). In the two other preference structures, respondents found provider choice more important than aspects related to quality of maternity care. CONCLUSIONS: In a country with presumed high-quality maternity care like the Netherlands, about half of pregnant women prefer being able to choose their maternity care provider over organisational factors that might imply better quality of care. A comparable amount of women find quality-related aspects most important when choosing a maternity care provider and are willing to accept limitations in their choice of provider. These insights are relevant for policy makers in order to be able to design a bundled payment model which justify the preferences of all pregnant women.

Cost-effectiveness of mandatory bicycle helmet use to prevent traumatic brain injuries and death.

BACKGROUND: Traumatic brain injury (TBI) is the main cause of mortality and severe morbidity in cyclists admitted to Dutch emergency departments (EDs). Although the use of bicycle helmets is an effective way of preventing TBI, this is uncommon in the Netherlands. An option to increase its use is through a legal enforcement. However, little is known about the cost-effectiveness of such mandatory use of helmets in the Dutch context. The current study aimed to assess the cost-effectiveness of a law that enforces helmet use to reduce TBI and TBI-related mortality. METHODS: The cost-effectiveness was estimated through decision tree modelling. In this study, wearing bicycle helmets enforced by law was compared with the current situation of infrequent voluntary helmet use. The total Dutch cycling population, consisting of 13.5 million people, was included in the model. Model data and parameters were obtained from Statistics Netherlands, the National Road Traffic Database, Dutch Injury Surveillance System, and literature. Effects included were numbers of TBI, death, and disability-adjusted life years (DALY). Costs included were healthcare costs, costs of productivity losses, and helmet costs. Sensitivity analysis was performed to assess which parameter had the largest influence on the incremental cost-effectiveness ratio (ICER). RESULTS: The intervention would lead to an estimated reduction of 2942 cases of TBI and 46 deaths. Overall, the incremental costs per 1) death averted, 2) per TBI averted, and 3) per DALY averted were estimated at 1) € 2,002,766, 2) € 31,028 and 3) € 28,465, respectively. Most favorable were the incremental costs per DALY in the 65+ age group: € 17,775. CONCLUSIONS: The overall costs per DALY averted surpassed the Dutch willingness to pay threshold value of € 20,000 for cost-effectiveness of preventive interventions. However, the cost per DALY averted for the elderly was below this threshold, indicating that in this age group largest effects can be reached. If the price of a helmet would reduce by 20%, which is non-hypothetical in a situation of large-scale purchases and use of these helmets, the introduction of this regulation would result in an intervention that is almost cost-effective in all age groups.

Ranking Preventive Interventions from Different Policy Domains: What Are the Most Cost-Effective Ways to Improve Public Health?

It is widely acknowledged that in order to promote public health and prevent diseases, a wide range of scientific disciplines and sectors beyond the health sector need to be involved. Evidence-based interventions, beyond preventive health interventions targeting disease risk factors and interventions from other sectors, should be developed and implemented. Investing in these preventive health policies is challenging as budgets have to compete with other governmental expenditures. The current study aimed to identify, compare and rank cost-effective preventive interventions targeting metabolic, environmental, occupational and behavioral risk factors. To identify these interventions, a literature search was performed including original full economic evaluations of Western country interventions that had not yet been implemented in the Netherlands. Several workshops were held with experts from different disciplines. In total, 51 different interventions (including 13 cost saving interventions) were identified and ranked based on their incremental cost-effectiveness ratio (ICER) and potential averted disability-adjusted life years (DALYs), resulting in two rankings of the most cost-effective interventions and one ranking of the 13 cost saving interventions. This approach, resulting in an intersectoral ranking, can assist policy makers in implementing cost-effective preventive action that considers not only the health sector, but also other sectors.

A social cost-benefit analysis of two One Health interventions to prevent toxoplasmosis.

In the Netherlands, toxoplasmosis ranks second in disease burden among foodborne pathogens with an estimated health loss of 1,900 Disability Adjusted Life Years and a cost-of-illness estimated at €45 million annually. Therefore, effective and preferably cost-effective preventive interventions are warranted. Freezing meat intended for raw or undercooked consumption and improving biosecurity in pig farms are promising interventions to prevent Toxoplasma gondii infections in humans. Putting these interventions into practice would expectedly reduce the number of infections; however, the net benefits for society are unknown. Stakeholders bearing the costs for these interventions will not necessary coincide with the ones having the benefits. We performed a Social Cost-Benefit Analysis to evaluate the net value of two potential interventions for the Dutch society. We assessed the costs and benefits of the two interventions and compared them with the current practice of education, especially during pregnancy. A 'minimum scenario' and a 'maximum scenario' was assumed, using input parameters with least benefits to society and input parameters with most benefits to society, respectively. For both interventions, we performed different scenario analyses. The freezing meat intervention was far more effective than the biosecurity intervention. Despite high freezing costs, freezing two meat products: steak tartare and mutton leg yielded net social benefits in both the minimum and maximum scenario, ranging from €10.6 million to €31 million for steak tartare and €0.6 million to €1.5 million for mutton leg. The biosecurity intervention would result in net costs in all scenarios ranging from €1 million to €2.5 million, due to high intervention costs and limited benefits. From a public health perspective (i.e. reducing the burden of toxoplasmosis) and the societal perspective (i.e. a net benefit for the Dutch society) freezing steak tartare and leg of mutton is to be considered.

Prospects of toxoplasmosis control by cat vaccination.

INTRO: Toxoplasmosis has high disease burden in the Netherlands and in the rest of Europe. It can be acquired directly by ingestion of Toxoplasma gondii (T. gondii) oocysts shed by infected cats, or indirectly via consumption of undercooked meat from infected livestock. Cat vaccination has been proposed for reducing oocyst-acquired human infections but it remains unclear whether such an intervention can be effective. In this study we quantified the effects of using cat vaccination on reducing oocyst-originated T. gondii human infections. METHOD: By using a disease dynamics compartmental model for T. gondii infections in cats and mice we studied the effects of a hypothetical cat vaccine on the presence of T. gondii oocysts in the environment. A fitted dose response model was used to assess the effect of oocyst reduction on the expected human infections. RESULTS: For rats, mice and pigs, and possibly intermediate hosts in general, ingestion of one oocyst provides 30%-60% probability of T. gondii infection. Assuming a favourable ideal scenario where vaccination completely prevents oocyst shedding and predation rate is of one mouse per week per cat, eight cats can be left susceptible in order to achieve elimination and stop oocyst-originated transmission, independent of the total cat population. Considering populations of 1000, 100, 50 and 20 cats, cat vaccination coverage of 94%, 68%, 54% and 35%, respectively, would reduce expected oocyst-originated human cases by 50%. CONCLUSION: For attaining elimination of oocyst-originated human infections, only few cats may remain unvaccinated, regardless of the cat-population size, and only a few more cats may remain unvaccinated for reducing infections substantially. Such vaccination coverages can in practice be achieved only when small cat-populations are considered, but in larger cat-populations the large efficacy and vaccination coverage needed are unfeasible.

Selenite enrichment broth to improve the sensitivity in molecular diagnostics of Salmonella.

Selenite enrichment broth (SEB) is used to optimize the recovery of Salmonella enterica subspecies enterica from stool samples. Compared to a direct culture approach, it enhances culture yield by reducing growth of faecal coliforms and faecal streptococci. Over the course of seven years from 2000 to 2017, 47,235 faecal samples were tested with a Salmonella PCR. We investigated the added value of using SEB in combination with faeces for DNA extraction, in order to improve the sensitivity of molecular diagnostics for detection of Salmonella. A Salmonella enterica subspecies enterica strain was tested for growth characteristics, with and without incubation in SEB, to determine the impact of Selenite enrichment in the Salmonella PCR. Retrospectively, a total of 102 Salmonella enterica subspecies enterica PCR positive faecal samples were re-analysed. DNA extraction was performed with the EasyMag® and MagNaPure96® system using three different input volumes of faeces and SEB. Prospectively, 114 Salmonella PCR positive faecal samples were retested within 2 days using five different input volumes for DNA extraction. Retrospectively, PCR that used SEB as part of input in the DNA extraction, 7/102 (7%) Salmonella PCR positive samples were additionally detected compared to no use of SEB. Of these, Salmonella enterica subspecies enterica serovariation Thompson, Enteritidis, 9,12:l.v and Senftenberg have been outbreak related in the past. Prospectively results were combined in collaboration with another microbiology laboratory, 15/114 (13.2%) additional specimens were detected with the Salmonella PCR, including processing Selenite enrichment broth. In conclusion, of the total 47,235 feacal samples, with SEB the prevalence of a positive PCR for Salmonella is 2.2%. Of these 2.2% positive Salmonella PCRs, 0.4% was not detected in culture. By using SEB an improved detection of Salmonella diagnostics could be realized and a substantial part of 13,2% additional Salmonella cases could be detected.

Cost-effectiveness of screening for chronic hepatitis B and C among migrant populations in a low endemic country.

BACKGROUND: Chronic infection with hepatitis B or C virus (HBV/HCV) can progress to cirrhosis, liver cancer, and even death. In a low endemic country as the Netherlands, migrants are a key risk group and could benefit from early diagnosis and antiviral treatment. We assessed the cost-effectiveness of screening foreign-born migrants for chronic HBV and/or HCV using a societal perspective. METHODS: The cost-effectiveness was evaluated using a Markov model. Estimates on prevalence, screening programme costs, participation and treatment uptake, transition probabilities, healthcare costs, productivity losses and utilities were derived from the literature. The cost per Quality Adjusted Life Year (QALY) gained was estimated and sensitivity analyses were performed. RESULTS: For most migrant groups with an expected high number of chronically infected cases in the Netherlands combined screening is cost-effective, with incremental cost-effectiveness ratios (ICERs) ranging from €4,962/QALY gained for migrants originating from the Former Soviet Union and Vietnam to €9,375/QALY gained for Polish migrants. HBV and HCV screening proved to be cost-effective for migrants from countries with chronic HBV or HCV prevalence of ≥0.41% and ≥0.22%, with ICERs below the Dutch cost-effectiveness reference value of €20,000/QALY gained. Sensitivity analysis showed that treatment costs influenced the ICER for both infections. CONCLUSIONS: For most migrant populations in a low-endemic country offering combined HBV and HCV screening is cost-effective. Implementation of targeted HBV and HCV screening programmes to increase early diagnosis and treatment is important to reduce the burden of chronic hepatitis B and C among migrants.

Consequences of restricted STI testing for young heterosexuals in the Netherlands on test costs and QALY losses.

BACKGROUND: Due to rising costs caused by increasing demand for sexually transmitted infection (STI) care, the Dutch government changed the funding of STI clinics. In 2015, a more restrictive testing policy was introduced with syphilis and HIV tests only on indication for younger, heterosexual clients. We evaluated intended savings and missed syphilis and/or HIV infections and explored efficiency of possible test policies. METHODS: Using surveillance data from 2011 to 2013 with extensive testing for all, we estimated effects of restrictive testing on test costs, number of infections missed, costs per Quality Adjusted Life Year (QALY) lost, and calculated the net monetary benefit from a government perspective. RESULTS: The 2015 policy led to estimated savings of €1.1 million, while missing approximately three HIV infections and seven syphilis infections annually. Savings were €435,000/QALY lost. If testing second-generation immigrants for syphilis and HIV, savings rose to €525,000/QALY lost. Offering an HIV test when diagnosed with chlamydia or gonorrhoea savings were €568,000/QALY lost. In a sensitivity analysis, the willingness-to-pay threshold had the highest impact on results. CONCLUSIONS: The 2015 testing policy resulted in a modest decline of detected HIV and syphilis infections, generating substantial savings. Syphilis and HIV tests for both first- and second-generation immigrants and an HIV test in case of positive chlamydia or gonorrhoea diagnosis could reduce missed infections in a cost-effective way.

Ebola in the Netherlands, 2014-2015: costs of preparedness and response.

The recent epidemic of Ebola virus disease (EVD) resulted in countries worldwide to prepare for the possibility of having an EVD patient. In this study, we estimate the costs of Ebola preparedness and response borne by the Dutch health system. An activity-based costing method was used, in which the cost of staff time spent in preparedness and response activities was calculated based on a time-recording system and interviews with key professionals at the healthcare organizations involved. In addition, the organizations provided cost information on patient days of hospitalization, laboratory tests, personal protective equipment (PPE), as well as the additional cleaning and disinfection required. The estimated total costs averaged €12.6 million, ranging from €6.7 to €22.5 million. The main cost drivers were PPE expenditures and preparedness activities of personnel, especially those associated with ambulance services and hospitals. There were 13 possible cases clinically evaluated and one confirmed case admitted to hospital. The estimated total cost of EVD preparedness and response in the Netherlands was substantial. Future costs might be reduced and efficiency increased by designating one ambulance service for transportation and fewer hospitals for the assessment of possible patients with a highly infectious disease of high consequences.

Cost of Nosocomial Outbreak Caused by NDM-1-Containing Klebsiella pneumoniae in the Netherlands, October 2015-January 2016.

During October-December 2015, 29 patients in a hospital in the Netherlands acquired nosocomial infection with a multidrug-resistant, New Delhi-metallo-ß-lactamase-positive Klebsiella pneumoniae strain. Extensive infection control measures were needed to stop this outbreak. The estimated economic impact of the outbreak was $804,263; highest costs were associated with hospital bed closures.

The cost of Lyme borreliosis.

Background: Lyme borreliosis (LB) is the most frequently reported tick-borne infection in Europe and North America. The aim of this study was to estimate the cost-of-illness of LB in the Netherlands. We used available incidence estimates from 2010 for tick bite consultations and three symptomatic LB outcomes: erythema migrans (EM), disseminated LB and Lyme-related persisting symptoms. The cost was estimated using these incidences and the average cost per patient as derived from a patient questionnaire. We estimated the cost from a societal perspective, including healthcare cost, patient cost and production loss, using the friction cost method and a 4% annual discount rate. Tick bites and LB in 2010 led to a societal cost of €19.3 million (95% CI 15.6-23.4; 16.6 million population) for the Netherlands. Healthcare cost and production loss each constituted 48% of the total cost (€9.3 and €9.2 million/year), and patient cost 4% (€0.8 million/year). Of the total cost, 37% was related to disseminated LB, followed by 27% for persisting symptoms, 22% for tick bites and 14% for EM. Per outcome, for an individual case the mean cost of disseminated LB and Lyme-related persisting symptoms was both around €5700; for EM and GP consultations for tick bites this was €122 and €53. As an alternative to the friction cost method, the human capital method resulted in a total cost of €23.5 million/year. LB leads to a substantial societal cost. Further research should therefore focus on additional preventive interventions.

The whole story: a systematic review of economic evaluations of HPV vaccination including non-cervical HPV-associated diseases.

INTRODUCTION: Many economic evaluations of HPV vaccination have been published, but most have focused on the prevention of cervical disease as a primary health outcome. The cost-effectiveness of vaccination is likely to be underestimated if not all HPV-associated diseases are taken into account. In this review, we assess the influence of non-cervical HPV-associated diseases on the incremental cost-effectiveness ratio (ICER) of preadolescent HPV vaccination. Areas covered: We systematically searched the literature and identified 18 studies that included non-cervical diseases in the estimates of cost-effectiveness of HPV-vaccination. When taking other HPV-related diseases into account compared to not including such other diseases, the mean ICERs were 2.85 times more favorable for girls only vaccination and 3.89 times for gender neutral vaccination. Expert commentary: Including non-cervical diseases in economic evaluations of HPV vaccination programs makes it more likely that the ICER falls beneath accepted cost-effectiveness thresholds and therefore increases the scope for gender neutral vaccination.

The economic burden of a Salmonella Thompson outbreak caused by smoked salmon in the Netherlands, 2012-2013.

Background: In 2012, the Netherlands experienced the most extensive food-related outbreak of Salmonella ever recorded. It was caused by smoked salmon contaminated with Salmonella Thompson during processing. In total, 1149 cases of salmonellosis were laboratory confirmed and reported to RIVM. Twenty percent of cases was hospitalised and four cases were reported to be fatal. The purpose of this study was to estimate total costs of the Salmonella Thompson outbreak. Methods: Data from a case-control study were used to estimate the cost-of-illness of reported cases (i.e. healthcare costs, patient costs and production losses). Outbreak control costs were estimated based on interviews with staff from health authorities. Using the Dutch foodborne disease burden and cost-of-illness model, we estimated the number of underestimated cases and the associated cost-of-illness. Results: The estimated number of cases, including reported and underestimated cases was 21 123. Adjusted for underestimation, the total cost-of-illness would be €6.8 million (95% CI €2.5-€16.7 million) with productivity losses being the main cost driver. Adding outbreak control costs, the total outbreak costs are estimated at €7.5 million. Conclusion: In the Netherlands, measures are taken to reduce salmonella concentrations in food, but detection of contamination during food processing remains difficult. As shown, Salmonella outbreaks have the potential for a relatively high disease and economic burden for society. Early warning and close cooperation between the industry, health authorities and laboratories is essential for rapid detection, control of outbreaks, and to reduce disease and economic burden.

Economic Costs of Measles Outbreak in the Netherlands, 2013-2014.

In 2013 and 2014, the Netherlands experienced a measles outbreak in orthodox Protestant communities with low measles-mumps-rubella vaccination coverage. Assessing total outbreak costs is needed for public health outbreak preparedness and control. Total costs of this outbreak were an estimated $4.7 million.

The burden of Lyme borreliosis expressed in disability-adjusted life years.

BACKGROUND: Lyme borreliosis (LB) is the most commonly reported tick-borne infection in Europe and North America. In the last 15 years a 3-fold increase was observed in general practitioner consultations for LB in the Netherlands. To support prioritization of prevention and control efforts for LB, we estimated its burden expressed in Disability-Adjusted Life Years (DALYs). METHODS: We used available incidence estimates for three LB outcomes: (i) erythema migrans (EM), (ii) disseminated LB and (iii) Lyme-related persisting symptoms. To generate DALYs, disability weights and duration per outcome were derived using a patient questionnaire including health-related quality of life as measured by the EQ-5D. RESULTS: We estimated the total LB burden for the Netherlands in 2010 at 10.55 DALYs per 100,000 population (95% CI: 8.80-12.43); i.e. 0.60 DALYs for EM, 0.86 DALYs for disseminated LB and 9.09 DALYs for Lyme-related persisting symptoms. Per patient this was 0.005 DALYs for EM, 0.113 for disseminated LB and 1.661 DALYs for a patient with Lyme-related persisting symptoms. In a sensitivity analysis the total LB burden ranged from 7.58 to 16.93 DALYs per 100,000 population. CONCLUSIONS: LB causes a substantial disease burden in the Netherlands. The vast majority of this burden is caused by patients with Lyme-related persisting symptoms. EM and disseminated Lyme have a more modest impact. Further research should focus on the mechanisms that trigger development of these persisting symptoms that patients and their physicians attribute to LB.

[More efficient testing policy at STI clinics]. / Doelmatiger testbeleid van soa-poliklinieken GGD.

OBJECTIVE: To assess the efficiency of the testing policy change in 2012 in sexually transmitted infection (STI) outpatient clinics: persons who attend the clinic and are aged < 25 years without other risk factors are initially tested only for chlamydia, and only in the event of a positive test result will they be tested for other STIs. Other possible changes in the STI testing policy were explored. DESIGN: Explorative study. METHOD: To test the new policy, data from STI outpatient clinics from 2011 were used for the risk group "young people under 25 years of age without other STI risks". Other groups who visited STI outpatient clinic were selected from the data from the STI outpatient clinics from 2012. Test cost savings and missed STIs were calculated if STI outpatient clinic attendees from these risk groups first received only a chlamydia or a combination test (chlamydia and gonorrhoea). Test cost savings were divided by the number of missed STIs as a measure of efficiency. RESULTS: The policy change led to an annual test cost saving of € 1.1 million but missed 31 gonorrhoea infections (€ 36,200 at the cost of one missed gonorrhoea infection). Using a combination test for chlamydia and gonorrhoea in heterosexual individuals visiting the clinic aged < 25 years and not from a STI-endemic country could lead to test costs savings of € 3.8 million. Savings at the cost of one missed STI would be about € 350,000; 4 HIV and 7 syphilis infections would have been missed. CONCLUSION: The national policy change has led to a substantial reduction in test costs. The policy measure would be even more efficient if a combination test for chlamydia and gonorrhoea were applied. Testing using a combination test in all heterosexual individuals who attend the clinic and are aged < 25 years and not from an STI-endemic country would lead to additional savings.

[Societal costs of asthma, COPD and respiratory allergy]. / Maatschappelijke kosten van astma, COPD en respiratoire allergie.

OBJECTIVE: To estimate the societal costs of asthma, COPD and respiratory allergy for the year 2007 and future healthcare costs for the period 2007-2032. DESIGN: Descriptive study. METHODS: Representative registries were used to estimate the healthcare costs of asthma, COPD and respiratory allergy for the year 2007. A simulation model for asthma and COPD and a demographic projection for respiratory allergy were used to determine future healthcare costs. Production losses due to sick leave and work incapacity were calculated using the friction-cost method. RESULTS: Total healthcare costs for asthma, COPD and respiratory allergy in 2007 were estimated at 287, 415 and 103 million euros respectively; on average 530, 1400 and 170 euros per patient with asthma, COPD and respiratory allergy. Average costs of sick leave for asthma were on average 1200 euros and for COPD 1900 euros per employee per year. The costs of work incapacity of an employee with COPD were 1200 euros. There is expected to be an increase in the number of patients from 443,000 in 2007 to 567,000 in 2032 for asthma and from 335,000 to 600,000 for COPD. The number of patients with a respiratory allergy are expected to remain approximately stable at 625,000 patients. The healthcare costs for respiratory allergy are expected to rise by 73%, those for asthma to double, and those for COPD to triple. CONCLUSION: Patients with asthma and COPD have high healthcare costs. Sick leave makes up a large part of the costs of asthma and COPD. In addition, the costs of work incapacity for employees with COPD are high. The number of patients with asthma and COPD will rise in the coming decades, as well as the healthcare costs for these diseases.

Usefulness of primary care electronic networks to assess the incidence of chlamydia, diagnosed by general practitioners.

BACKGROUND: Chlamydia is the most common curable sexually transmitted infection (STI) in the Netherlands. The majority of chlamydia diagnoses are made by general practitioners (GPs). Baseline data from primary care will facilitate the future evaluation of the ongoing large population-based screening in the Netherlands. The aim of this study was to assess the usefulness of electronic medical records for monitoring the incidence of chlamydia cases diagnosed in primary care in the Netherlands. METHODS: In the electronic records of two regional and two national networks, we identified chlamydia diagnoses by means of ICPC codes (International Classification of Primary Care), laboratory results in free text and the prescription of antibiotics. The year of study was 2007 for the two regional networks and one national network, for the other national network the year of study was 2005. We calculated the incidence of diagnosed chlamydia cases per sex, age group and degree of urbanization. RESULTS: A large diversity was observed in the way chlamydia episodes were coded in the four different GP networks and how easily information concerning chlamydia diagnoses could be extracted. The overall incidence ranged from 103.2/100,000 to 590.2/100,000. Differences were partly related to differences between patient populations. Nevertheless, we observed similar trends in the incidence of chlamydia diagnoses in all networks and findings were in line with earlier reports. CONCLUSIONS: Electronic patient records, originally intended for individual patient care in general practice, can be an additional source of data for monitoring chlamydia incidence in primary care and can be of use in assessing the future impact of population-based chlamydia screening programs. To increase the usefulness of data we recommend more efforts to standardize registration by (specific) ICPC code and laboratory results across the existing GP networks.