CD patients experienced poor HRQoL pre-treatment, which improved significantly after diagnosis and treatment. Many experienced a long delay to diagnosis, both from the first symptoms and from the first visit to a doctor. It is promising that patients diagnosed after 2004 reported better HRQoL than those diagnosed earlier and that the delay in diagnosis has decreased during recent decades; however, many still experience too long a delay. There has been a pronounced increase in median age at diagnosis, from 2 to 46 years in recent decades, illustrating that CD has changed from presenting as a childhood disease to being a disease affecting all ages.
This is a large study with a high response rate. A strength is that we used a validated HRQoL instrument and compared HRQoL for the CD population with that of a general population. The approach of asking CD respondents about HRQoL both before and after initiated CD treatment has only been tried once before [5
]. Our study is unique in that results for males and females are presented separately, and there is a more thorough analysis of factors that affect HRQoL. Further, we add results concerning how diagnostic delay has changed over time, also taking age and sex into consideration.
We believe that our findings are of great value for an increased understanding of how CD and its diagnostics affect people, despite some potential biases. We cannot be sure that our results are representative for the whole Swedish CD population. However, even if the results are only valid for responders (66% of invited) to the questionnaire within our study population (members of the Swedish Society for Coeliacs which correspond to about 60% of Swedish adults with CD), they nevertheless show an experienced burden for a sample representing about 40% of Swedish adults with CD, irrespective of age. The general population in our study is limited to northern Sweden while the CD population comes from the entire country. However, regarding HRQoL, there was no statistical difference between persons with CD from the northern part of the country and the rest of Sweden. A recall bias might appear as some responders had their CD diagnosis long ago. This might cause both a low estimate of HRQoL pre-treatment, as well as an overestimate of the delay from first symptoms indicative of CD to CD diagnosis. However, the usual recall pattern is to report fewer episodes of ill health, and therefore previous health problems might instead be underestimated.
A long diagnostic delay has been shown earlier in several studies [4
]. However, awareness of CD has increased in recent decades and serological testing has been introduced and improved. Similar to findings in our study, a shortened diagnostic delay over time was found in the UK [5
], but was not observed in Canada [4
]. Neither study considered increasing age at diagnosis, a factor that might affect their results as well.
The positive effects of diagnosis and treatment we report here are also supported by others [5
]. Our results confirm that CD females experience a lower HRQoL than males [13
]. The difference is even larger before initiated treatment, which indicates that living with untreated CD might be a greater burden for females. It is also interesting that treated CD patients reported a better HRQoL than the general population. This might be a result of an altered frame of reference, after experiencing poorer health, or due to adapting to a healthier life style after being diagnosed with a chronic disorder. Our study subjects reported an unexpectedly high rate of compliance with a gluten-free diet (96%), and it has been shown that better compliance is related to a better HRQoL [11
Despite increased awareness in society and in health care, many CD cases will be missed due to vague symptoms. Mass screening for CD has been raised as a possible option [28
]. CD mass screening fulfils most of the listed criteria for a medical mass screening adapted by WHO from Wilson and Jungner [29
]. However, knowledge concerning the natural history of CD and the cost-effectiveness of a CD mass screening is lacking [28
]. There are few health economic evaluation studies of a CD mass screening. Existing studies indicate that a screening might be cost-effective [32
], and that parents' willingness to pay for a CD mass screening on average is greater than the screening cost [34
]. It was recently estimated in the United States that the medical cost for clinically detected CD patients is reduced by $1764 the year following diagnosis as compared to the average cost during the preceding years [35
]. The fact that both cost savings and long-term health complications might differ between clinically diagnosed patients and screening detected CD must be taken into account, and there is a need for studies on this particular group [36