Tuberculosis (TB) continues to be the most common global disease, causing 1.5 million deaths in 2014, with approximately 9.6 million new cases occurring every year.1 In Spain, according to data from the Epidemiological Surveillance Network,2 5018 cases of TB were notified via the individualized mandatory reporting system in 2014, 3933 of which were classified as respiratory tuberculosis, with an incidence rate of 10.80 cases per 100,000 inhabitants. However, a study recently conducted by the Integrated Tuberculosis Research Program (PII TB) of the Spanish Society of Pulmonology and Thoracic Surgery (SEPAR)3 revealed significant under-reporting, ranging from 0% to 40% depending on the hospital, with a mean under-reporting rate of 14.4%.

The TB patient population worldwide and in Spain generates economic and social problems, giving rise to direct costs in the form of healthcare spending, and indirect costs, primarily in the form of days of work lost, and even years of life lost.4 Moreover, TB affects the working population and individuals with all kinds of difficulties (immigrants, HIV-infected individuals), so its socioeconomic impact is significant. Few studies have been published in Spain on the costs of TB,5–8 and those that have appeared are limited by their exclusive focus on hospitalization costs.

Our aim, then, was to analyze costs derived from the diagnosis and follow-up of TB and associated factors.

Several original articles have been published in recent years on the costs generated by various aspects of tuberculosis, showing how the distribution of costs varies depending on the economic resources of the country in question. The fewer the resources, the greater the spending derived from indirect costs in the post-diagnosis period, while in more highly developed regions, direct costs, in particular those generated by hospitalization, have the most impact.14

A recent study of all series published in the European Union, of which only 1 was conducted in Spain, showed that mean per-patient cost of drug-sensitive tuberculosis was €10,282 and €57,213 for MDR, 77% of which was derived from direct costs.15 In our study, which had a similar design, the percentage of expenditure attributed to direct costs was 86%, and mean cost per patient was lower, perhaps due to the small percentage of cases with resistance, including MDR. This is in line with previous studies in Spain that reported an overall rate of 9.2% for drug resistance and 1.9% for MDR.16 The lower impact of indirect costs may derive from our use of an employment rate of 59%, retrieved from the official employment survey data, for the calculation of costs derived from loss of productivity, in contrast to the 71% employment rate reported in the aforementioned series.15 Basing our calculations on a rate of 71% would have increased indirect costs by approximately 16%, which would give us a result more in line with that obtained in the European study. Nevertheless, that study showed striking variations among our neighboring countries, with mean costs ranging from €5691 to €8242 per patient. These differences were supported by a study performed in Denmark where the mean direct cost of TB was €10,509.17 In this country, as in Spain, the resistance rate is low, and therefore the results of the Danish authors are similar to ours.

In our series, costs were determined by hospitalization (accounting for 61% of total expenditure), drug susceptibility testing, DOT, sick leave, and chest CT. The impact of hospital costs has already been addressed by Montes-Santiago et al.,8 who observed that in Spain in 2006, the cost of hospitalization for tuberculosis amounted to €30.8 million. Assuming that hospitalization accounts for 70% of costs, the total cost of tuberculosis was €40 million, representing 0.7% of total public expenditure. These authors also observed a slight fall in costs coinciding with fewer hospital admissions between 1999 and 2006. Similarly, in another series conducted in Germany,12 the cost of a hospital stay was practically 9 times that of treating the patient on an exclusively outpatient basis. The same occurred in Denmark, where hospitalization accounts for 81% of costs.17 Furthermore, in a national tuberculosis program in South Africa, Pooran et al.18 determined that costs generated by hospitalization accounted for a significant portion of total costs: 56% in their case. Considering the above, hospital admission for TB should be avoided as far as possible and limited to cases recommended in clinical guidelines19 (severe cases or disease complications and impossibility to isolate the patient at home), in order to reduce the risk of transmission and disease-related costs. Nonetheless, the percentage of hospital admissions for tuberculosis remains high, both in our sample, where it was 59%, and in other national and international reports, which range from 52% to 78%,7,8,11,20,21 although the reason for this high proportion remains unclear. Thus, a strategy aimed at reducing hospital stays would reduce costs, as has already been observed in some regions which have managed to achieve rates as low as 34%.7 If we take this figure and extrapolate our results to the number of TB cases notified in Spain in 2014, we estimate that savings of €14 million could be achieved.

Steffen et al.22 found that costs of DOT were significantly higher than the cost of self-administered treatment, but that it increased, albeit insignificantly, the rate of treatment completion. Furthermore, a recent meta-analysis of studies performed mainly in south-east Asia and English-speaking countries showed that DOT does not improve outcomes in terms of microbiological cure, prevention of relapse or development of acquired resistance compared to self-administered medication,23 so it seems reasonable to limit the use of DOT in countries with low to medium incidence to populations in special situations. In our setting, it is reserved solely for complicated cases or individuals with severe social problems who cannot follow their regimen normally. DOT is currently used in less than 25% of patients.

Our results also suggest that expenditure can also be reduced by decreasing the duration of sick leave, since earlier studies have shown that it has a significant impact on costs.17 We must bear in mind that the main objective is to reduce the transmission of the disease and that, with standard treatment, contagiousness is significantly reduced after 3 weeks.19 After that time, isolation measures can be lifted and the subject can return to the workplace. This period coincides with the mean number of days of sick leave identified in our study, so we can surmise that this aspect is not one of the most important in our setting.

From all of the above, then, we can conclude that avoiding unnecessary hospital stays is the only way to reduce costs. Nevertheless, it is important to point out that, since TB gives rise to significant healthcare costs (extrapolating the data from our study to cases notified in 2015, expenditure would amount to €51,500,000), reducing the number of cases is the surest way to reduce costs. This, in turn, highlights the importance of such proven cost-effective strategies as contact tracing and treatment of latent tuberculous infection.

Our study is limited in several ways. Similarly to the studies discussed above,12,13 we have only included estimated indirect costs derived from loss of productivity, rehabilitation therapies, and contact tracing, and have probably underestimated the real costs by failing to include other indirect costs, such as transport, food, electricity, maintenance, and human resources incurred by personnel caring for these patients, and the costs of primary care. However, many of these costs would have greater impact in countries lacking in resources and universal healthcare provision, or in populations with a significant proportion of patients with special requirements (which does not seem to be the case in our series). Moreover, the diagnosis and follow-up of these patients is generally performed in specialized care. We also did not include costs derived from pharmacological side effects, since most of them are reversible after discontinuation of the causative drug, and do not require further measures. The cost of adjuvant medication for gastrointestinal side effects is negligible. We therefore believe that, while it may be interesting to include these costs, they would not significantly affect the final outcomes of our study, and excluding them does not affect the validity of our conclusions. Finally, we used costing data from only 2 health services in our calculations, so we are aware that due to the variations between the different autonomous communities and the fact that only 9 of these participated in the study, our study may not reflect the exact cost of tuberculosis. However, we would like to point out that we aimed to use our data to obtain an approximate estimation, and we believe that we have achieved this in a reasonable enough manner for our study to have meaning in this setting.

Tuberculosis gives rise to significant healthcare costs, generated by hospitalizations, imaging studies, directly observed treatment and the need for sick leave. Hospital admission appears to be the factor with the most impact, so strategies aimed at decreasing hospital stays would be essential if costs have to be reduced.

This project was funded by SEPAR grant 136/2013.

José Antonio Gullón: study concept. Writing, critical reading, review and final approval of the manuscript. Analysis of results.

José María García: study concept. Critical reading, review and final approval of the manuscript. Analysis of results.

Manuel Ángel Villanueva and Fernando Álvarez-Navascues: study concept. Analysis of results.

Teresa Rodrigo and Joan Caylá: critical reading, review and final approval of the manuscript. Analysis of results.

Martí Casals: statistical analysis.

Marta García-Clemente, Luis Anibarro, María Ángeles Jiménez, Ana Bustamante, Antón Penas and José Antonio Caminero: critical reading, review and final approval of the manuscript.

PII TB Working Group: data collection.

The authors state that they have no conflict of interests.