We found that at least 60% of patients who are treated for COPD in Denmark have never been treated for COPD in a hospital setting (secondary care). The average individual total health care cost of a patient who have had secondary care treatment for COPD is between 2,19 and 2,58 times higher than that of a patient who have only been treated for COPD in primary care, and the range of individual costs is very wide and highly overlapping between secondary care- and primary-care-only patients.
Secondary care patients have higher individual costs than primary-care-only for most types of pharmaceuticals and services in both primary and secondary care. It follows the intentions of the Danish health care system that severe cases are referred to secondary care and though the study lacks clinical characteristics of the patients (spirometry measures, dyspnoea score, and exacerbation frequency) our results, especially the higher costs for GP home visits, indicates a higher severity among secondary-care patients than primary-care-only 22. This difference in case severity between primary-care-only and secondary care impairs any fair comparison of costs and our findings should not lead to the unsupported conclusion that the current patients with COPD in secondary care could have been treated in primary care at a lower cost. Our intentions when comparing the primary-care-only patients’ consumption of health care resources to that of secondary-care are rather to relate the burden of disease in the two populations and explore any differences in the populations’ specified use of healthcare resources.
In Denmark, the vast majority of primary care COPD treatment is delivered by GPs, clearly indicated by the low costs to specialists in internal medicine even in the primary-care-only population (Table 4). Shortly after the present study period and among other reasons to save hospital resources, the Danish Regions and the GPs made a new agreement that the GPs should take responsibility for treating a larger proportion of the COPD population and therefore receive a capitation fee (247 € per year) replacing the previous fees for daytime consultations, telephone calls, and E-mails used in this study 23. Notably, the GP costs in Table four sum to somewhat more than 247 € because the daytime consultation costs include fees for laboratory test and other services not covered by the new capitation fee. We found that already before the new agreement, the Danish GPs were responsible for treatment of most patients with COPD, and usually without any involvement of the hospitals.
Prior studies, including two from Denmark, have found that patients with COPD have three to five times higher health care costs compared to age- and gender matched control persons without COPD4 5 7 8 10 15. These studies primarily sampled COPD patients from secondary care and tended to include the primary-care-only patients in the non-COPD control group. Since primary-care-only patients cost more than non-COPD patients but less than secondary care patients, moving them from the COPD to the non-COPD group will increase the per patient costs in both groups. Thus, the potential bias in cost difference can go either way. However, the estimates of total costs become substantially lower when not including the primary-care-only patients.
Lack of spirometry data lowers the validity of the COPD diagnoses in our study. We used the RUKS’ COPD algorithm that was developed by Sundhedsdatastyrelsen [The Danish Board of Health Data] to identify patients with COPD in the national registries. The algorithm intentionally favours specificity over sensitivity. For secondary care it means that the diagnoses used to define COPD are highly specific, but some hospital treatments of COPD are falsely coded as pneumonia or other not COPD diagnoses leading the patient to be misclassified as primary-care-only or not even included in the study 18. Also, the specificity of the COPD diagnoses in primary-care-only is high since most of the patients purchased LAMA at least twice in the inclusion period, which is a rather expensive drug specifically indicated for moderate to severe COPD. On the other hand, the sensitivity is low. More than twice the included number of patients redeemed prescriptions on pharmaceuticals for obstructive lung disease but did not fulfil the algorithm. Some of these patients probably have asthma and not COPD but, considering that we only include + 30-year-olds, many of the patients most likely have COPD. A known error in the recording of indication codes probably caused some primary-care-only patients not to be included. Prescription of many respiratory pharmaceuticals are by default coded with the indication codes for asthma or bronchospasm and these default codes have been recorded in the registry even if the prescriber corrected the indication on the prescription. That is probably why the primary-care-only cohort consisted of far more LAMA- than LABA- or shortacting-beta-2-agonist users. Consequently, our comparison analyses included only 114,555 patients while the Danish COPD prevalence studies report around 320,000 Danes to have COPD, some of these though estimated to have undiagnosed COPD or be diagnosed with COPD but not pharmaceutically treated for COPD 23.
Despite its known limitations, we used the RUKS’ algorithm partly to concur with the approach of Danish authorities but mostly to optimise the specificity of the COPD diagnoses, acknowledging that in primary care the COPD diagnoses may be less accurate than in hospitals. Even with this very restrictive approach we identified a large cohort of patients with primary-care-only COPD accounting for much of the total costs. RUKS provides sufficient case severity and accuracy of the COPD diagnoses to rely on the shown differences in resource allocation. For example, that patients with secondary care COPD are more likely than primary-care-only patients to use GPs and psychologists, but less likely to use primary care specialists and dentists. Intuitively, one could mistakenly assume that secondary-care patients would use the GP less often, but this is not the case. The secondary-care patients were identified via episodes of hospital care during the past five years, some of these episodes only lasting few days. However, COPD is a chronic progressive disease and therefore it is reasonable and customary to classify patients based on prior rather than only current hospital treatment. Inclusion of patients in the secondary-care COPD group based on only brief historic need for hospital treatment may explain why a substantial proportion of the secondary-care patients had lower costs of healthcare than the median of the primary-care-only patients. This is however the usual approach and our secondary care cost estimates are generally consistent with previous findings. A study based on the same Danish registries as this study estimated the total costs of healthcare for patients with COPD in secondary care during the period from 1998 to 2010. Compared to that study (and adjusted to 2016-prices) the present study found somewhat lower individual costs for pharmaceuticals (1794 € versus 1950 €) but considerably higher costs for primary- (729 € versus 564 €) and secondary health care (8717 € versus 6954 €) 10. Another Danish study estimated the primary- and secondary care costs in 2002 and reported similarly lower costs than our estimates 5. The differences in individual costs compared to the present study probably reflect the ongoing development of better but more complex and expensive health care services and that the prices of inhalator pharmaceuticals in Denmark have decreased. A Swedish study from 2013 found somewhat higher primary and secondary care COPD health care costs but lower costs of pharmaceuticals 4. All other available COPD cost studies have been based on populations, health care systems, or approaches incomparable to the present study. However, all studies agree that most costs relate to hospitalisations, often with comorbidities.
Our findings reflect a health care system where most patients with COPD are treated in primary care and the results are probably generalisable to other health care systems with a strong primary care sector e.g., the UK, the Netherlands, and Scandinavia.
Strengths and limitations
The cost data from Danish registries used in this study are highly complete and valid 17. All ATCR03 and with few exceptions all other drugs are on prescription. Based on the individual patient’s purchases in the past 365 days, the national electronic prescription system calculates a partial remuneration when buying a prescribed drug. False records of purchases are unlikely since all parts of the healthcare system use the same synchronised medication platform meaning that all purchases are immediately exposed to the patient and all involved healthcare personnel. Primary and secondary care costs in the study are equal to the actual payments to the GPs and hospitals. However, the study does not cover the healthcare costs of services provided by the Danish municipalities, including nursing, prevention, and rehabilitation, and likewise not societal costs related to production losses and absence from work.
Implications
Our findings imply that health care planners and researchers doing population- and cost studies of COPD in countries with a strong primary care should be aware that most patients who are treated for COPD are solely treated for the disease in primary care. These patients appear frequently in the secondary healthcare system but not directly with COPD. They do, however, account for a large share of the total health care costs of COPD that should not be overlooked when comparing and/or prioritizing disease-related health care resources.
Future studies should aim to further characterize and differentiate patients with COPD in different parts of the health care systems exploring the wide and overlapping range of individual costs. Health professionals, politicians, and patients think, plan, agree on, and draw pyramids where the most resource demanding COPD patients are supposed to be treated in secondary- and only milder cases in primary care 23. However, the substantial overlap of the individual costs of secondary-care and primary-care-only patients in Denmark may reflect the weaknesses of the pyramid mindset rather than the Danish healthcare systems’ inability to fit the COPD patients in the pyramid. Healthcare researchers describe and try to track COPD patients who are expected to be transferred forth and back between healthcare sectors, but the reality is often a far more complex integration of care.