In this prospective, nationally representative study we found that untreated adults with coeliac disease made more outpatient health care visits than the general population. In addition, implementation of a gluten-free diet resulted in the disappearance of this increased consumption of medical services. The burden of unrecognized coeliac disease was concentrated particularly in primary health care. In parallel to these findings, a significant reduction in the use of on-demand drugs and the number of antibiotic prescriptions was observed while on dietary treatment. To our knowledge, this was the first study to investigate sickness absence and consumption of on-demand medication among coeliac disease patients.
A possible explanation for the increased use of health care services and symptom-targeted medication prior to diagnosis might be related to the presence of diverse symptoms: untreated coeliac disease is known to be associated with various unspecific complaints – e.g. indigestion and heart burn [17
], regurgitation [18
], migraine [19
] and joint pain [20
], which may resolve on a gluten-free diet. It has also been suggested that active coeliac disease may be associated with an increased susceptibility to infections [21
]. Our findings suggest that the diagnosis and subsequent treatment of coeliac disease are able to reduce the burden of disease in the health care system in addition to the alleviated burden experienced by patients [14
Earlier data on the use of health care services in coeliac disease are limited. Two recent retrospective studies from the USA found that treatment with a gluten-free diet resulted in decreased medical costs due to reduced use of health care services among coeliac disease patients. However, these studies concentrated on direct costs and obtained study participants in high-volume referral centres or administrative claim registers [23
], which may limit extrapolation of the data to the whole coeliac disease population. It is of note that the main findings - excessive health care service use before the diagnosis of coeliac disease and reduction in the consumption of these services during a gluten-free diet - were in line, despite the difference in settings between these earlier trials and our current prospective nation-wide study. However, in contrast to the results reported by Long and associates [24
] we found no difference in the number of hospitalizations between the years prior to and following the diagnosis of coeliac disease. In addition, in the present study expenditure on laboratory services and imaging were not increased prior to diagnosis. Even though direct medical costs were not evaluated in the present study, the results of decreased use of health care services and pharmaceutical agents suggest decrease in costs for the health care system. In addition to the studies mentioned earlier, another recent study showed excess costs of undiagnosed symptomatic coeliac disease patients and highlighted a largely advantageous cost-benefit ratio for a diagnosis of the disease [25
]. From an ethical point of view, as the aforementioned studies have shown increased numbers of medical investigations before the diagnosis, it should be noticed how many unnecessary invasive procedures (such as bone biopsy and blood transfusions for unexplained anaemia, colonoscopy for abdominal pain, computed tomography for suspected inexistent neoplasms) could have been saved in these patients if the disease would have been diagnosed earlier.
Nowadays the proportion of coeliac disease patients suffering from severe gastrointestinal symptoms and malabsorption is decreasing and milder symptoms predominate. Consultations on these possibly vague and unspecific symptoms might add to the burden in primary health care, which patients first contact upon any complaints. Additionally, the diagnostics and follow-up of coeliac disease among adults are focused in primary health care in Finland [13
], all these aspects possibly explaining the increased use of primary health care services observed in the present study.
Even though the consumption of health care services among coeliac disease patients was reduced to the population level during one year on a gluten-free diet, further studies are needed to establish the long-term impact of dietary treatment. A recent study from Sweden reported that, in spite of a median of 4 years on a gluten-free diet, female coeliac disease patients used more health care services than non-coeliac controls [26
]. It was also shown that the majority of complaints were related to gastrointestinal symptoms, mental and behavioural disorders and diseases of the musculoskeletal system. There is further evidence that regardless of a long-term gluten-free diet and histological remission, coeliac disease patients may evince significant symptoms and impaired health-related quality of life [27
]. A recent study found that impaired quality of life in coeliac disease patients on a gluten-free diet is largely explained by coexistence of irritable bowel syndrome and reflux [29
It was somewhat surprising that the patients in our study reported no increased sickness absence from work prior to diagnosis. Actually, the number of days of absence was even lower than that among the general population. This would imply that currently the majority of coeliac disease patients present with relatively mild clinical symptoms. However, although untreated coeliac disease is known to be associated with increased anxiety and depression [30
], reduced vitality [31
] and sleeping disorders [32
], we did not here inquire in to the possible decrease in productivity among undetected coeliac disease patients. The reason why male but not female coeliac disease patients increased their number of days of absence from work in the follow-up remains unsolved. Possibly, once given a diagnosis of a chronic disease the patients may have thought to be “validated” or “vindicated” in being off work. Unfortunately, we could not ascertain whether sick leaves were concentrated during the period short after diagnosis or were evenly distributed along the follow-up period.
Even though decrease in the number of antibiotic prescriptions was not big it can be regarded as clinically significant. Two recent studies [33
] have investigated use of antibiotics and risk of developing Crohn’s disease or ulcerative colitis. They found that subjects with those diseases were more likely to have been prescribed antibiotics before the diagnosis. Shaw and associates [33
] speculated that the use of antibiotics could be a predisposing factor, whereas Virta and associates [34
] considered that frequent use of antibiotics may trigger the development of Crohn’s disease or be a sign of being prone to infections before the intestinal disease is diagnosed. Our hypothesis about coeliac disease patients is similar to the latter consideration and is supported by the fact that fewer patients had been prescribed antibiotics post than pre-diagnosis. However, whether increased use of antibiotics really is a predisposing factor to coeliac disease or sign of decreased immunity because of undetected coeliac disease is out of the scope of this study and needs further evaluations.
Interestingly, the use of vitamins, micronutrients and herbal products increased significantly after the diagnosis of coeliac disease. It has been reported that about 15-38% of untreated coeliac disease patients suffer from anaemia or nutritional deficiencies [35
]. Nevertheless, these are usually abolished on a gluten-free diet [35
], and implementation of specific dietary supplements after the diagnosis is not routinely recommended in current clinical guidelines [39
]. Consequently, we believe that in most cases the supplements were not prescribed by a physician but started voluntarily by the patients. This is somewhat worrying as increased use of vitamin and micronutrient supplements in suggested to be related to increased risk for cancer [40
]. However, there have been alarming results of dietary shortcomings among those following a gluten-free diet as patients have been reported to consume insufficient amounts of vitamins and micronutrients [41
]. This might be due to poor nutritional value of commercial gluten-free products or inadequate dietary choices. Thus, on the other hand, dietary supplements may be needed.
The fact that we used self-reported data might be considered a limitation to the study in that it may involve inaccuracies. However, a unique strength of such a setting in a nation-wide study was that by using self-reported data it was possible to explore all aspects of health care use instead of data captured in a single database. Subsequently, we were able to assess not only issues related to direct costs of care but also the indirect burden falling on coeliac disease patients themselves. However, similar methods have previously been used in studies concerning gastrointestinal disorders and a recall period covering the preceding twelve months in self-reported use of health care services and pharmaceutical agents has been shown to be feasible and reliable [43
]. Moreover, patients were asked to report issues similarly at baseline and in the follow-up, which makes the changes observed more reliable and test-re-test reliability for the key items was excellent. Likewise, the data on the general population were based on self-reported values asked similarly as in the present study. However, the study questionnaires for the cohorts were different which might have impacted the results. The response rate in this study was relatively low but comparable to those of earlier studies with similar study design [8
]. A weakness of the study is that because we were unable to ask about co-morbidities it was impossible to assess their possible impact to the results.