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Gastro-oesophageal reflux disease (GERD) is a common and costly illness that significantly impairs health-related quality of life (HRQOL), particularly among individuals with nocturnal symptoms.1 In the US, 14–20% of adults suffer from GERD-related symptoms at least once weekly.2, 3 Nocturnal symptoms are common among individuals with GERD; two nationwide telephonic surveys reported that between 74% and 79% of adults with heartburn (at least once weekly) also report experiencing night-time symptoms.1, 4 Only recently it has been recognized that the burden of night-time GERD may be significantly greater compared with that of daytime GERD. Farup et al. reported that adults with nocturnal manifestations of GERD report greater HRQOL impairment than GERD patients without night-time symptoms.1
The economic burden of GERD is considerable. Annual direct costs of GERD, which include doctor visits and pharmaceutical treatment, are estimated at $9.6 billion (year 2000 US dollars).5 Indirect costs of GERD because of reduced work productivity and time off work for doctor visits may be substantially higher than direct costs.1, 5 Henke et al. found that over 40% of patients with GERD report reduced work productivity because of their symptoms and estimated the annual cost of GERD-related work loss at $948/year based on reported annual salaries averaging about $35 000.6 In a study of service industry employees involving retrospective analyses of administrative health claims data, Dean et al. found that annual indirect costs because of productivity loss exceeded the combined direct costs of medical care and pharmacy use ($5193 vs. $1736, respectively).7 While the evidence suggests that indirect costs drive the economic burden of GERD, to our knowledge no studies have evaluated the indirect cost of nocturnal GERD.
One important factor thought to contribute to work productivity loss among GERD patients is sleep impairment caused by nocturnal symptoms. It is known that insomnia results in daytime fatigue and performance deficits and has been associated with impaired work productivity.8 Sleep disruption is common among individuals with night-time GERD, and may contribute considerably to HRQOL impairment.1, 4 Forty-one percent of adults who suffer from nocturnal heartburn believe that their symptoms interfere with their ability to function at work the following day.4 However, we are unaware of any studies that have attempted to quantify the impact of nocturnal symptoms on daytime work productivity in GERD or in any other disease populations.
To better understand the productivity impact of nocturnal GERD, we used an Internet-based survey to explore differences in work productivity, sleep impairment and HRQOL among employed adults with GERD and frequent nocturnal symptoms (GERD-FNS) vs. GERD cases with minimal or no nocturnal symptoms (GERD-NNS) and vs. non-GERD controls. We hypothesized that work productivity loss would be greater among those with GERD-FNS compared with GERD-NNS cases, and that sleep impairment would be greatest among those with GERD-FNS. Furthermore, we expected that employed individuals with GERD-FNS would have worse HRQOL compared with GERD-NNS cases and non-GERD controls.
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Our study has several important findings. First, work productivity was significantly worse among those with GERD-FNS compared with GERD-NNS (WPS, 12.2% vs. 5.4%; P < 0.0001). For a typical 40-h workweek, the burden of GERD-FNS as a result of GERD symptoms amounts to a weekly total work productivity loss of approximately 4.9 h vs. 2.2 h among those with GERD-NNS, for a difference of nearly 2.7 h. In assessing WPS by severity, we found that GERD-related symptom severity was strongly associated with work impairment, and that those with GERD-FNS were significantly more impaired than GERD-NNS patients within mild and moderate strata (comparison of severe GERD patients was consistent but did not reach statistical significance probably due to low number of patients with severe GERD-NNS). In addition, total work productivity worsened for each additional night of GERD symptoms from 4.5% work productivity loss among respondents reporting no nights with symptoms to 15.9% work productivity loss for those reporting four or more nights with symptoms. When applied to an employee with an average annual salary of $40 000, indirect costs due to GERD-FNS amount to $4133 annually when compared with $1831 due to GERD-NNS. This amounts to $2302 in annual costs per GERD-FNS case beyond the indirect costs per GERD-NNS case.
With a sizable proportion of GERD patients being working-age individuals, GERD-FNS may represent a significant economic burden to employers and society. Based on the work productivity losses reported among our employed population, the annual estimate of indirect costs in the US are $16.8 billion for GERD-FNS and $8.2 billion for GERD-NNS when the following are assumed: (i) there are 19 million GERD cases in the US;5 (ii) 75% of all GERD cases are working-age individuals;5 (iii) 60% of working-age individuals are actually employed19 and (vi) the ratio of GERD-FNS to GERD-NNS (as defined in our study) is 476/526.
At least three published studies have quantified work productivity loss due to GERD, and none of those studies examined differences between daytime and night-time symptoms. A recent survey of more than 1000 US employees found that total work productivity (including absenteeism and impairment while working) was reduced by an additional 10% among those with GERD when compared with non-GERD controls.7 For GERD participants, this amounted to over $5000 in annual lost productivity costs, somewhat higher than estimates from the present study ($4133 for GERD-FNS, $1831 for GERD-NNS). However, it should be noted that this previous survey employed only general health productivity measures (i.e. not specific to GERD), which may explain why those estimates are slightly higher than the annual GERD-specific costs reported here. From a study of the Swedish working population, it was reported that the GERD-specific work loss represented approximately 10.7 h lost per week due to both absence from work and diminished efficiency while at work.21 In contrast, a study of 150 GERD patients in a California Kaiser Permanente HMO reported GERD-related work productivity loss of only 3%, representing a loss of $940/year6 based on reported annual salaries averaging approximately $35 000. This was fairly comparable with results in our study, in which those with GERD-NNS had a GERD-specific work productivity loss of approximately 5%. However, work productivity loss in this Kaiser study was estimated using a structured interview rather than a standardized instrument, and the sample size of the GERD population was relatively small. Furthermore, it is unclear what proportion of subjects who participated in these studies were GERD-FNS patients.
Secondly, we found substantially greater sleep impairment among those with GERD-FNS when compared with GERD-NNS cases (P < 0.0001). Furthermore, we found that daytime sleepiness was also more pronounced among those with GERD-FNS compared with GERD-NNS cases, as demonstrated by the significantly higher mean total ESS score among the former group (P < 0.05). These results are consistent with previous findings of sleep impairment and reduced daytime functioning because of GERD-related night-time symptoms.4 It is known that the effects of partial sleep loss on daytime functioning can be cumulative.20 Hence, the negative impact of GERD-FNS on sleep during successive nights can lead to progressively higher daytime impairment, with these daytime effects compounding over time among the most symptomatic of GERD-FNS cases.
Thirdly, we found that GERD-FNS is associated with significantly worse HRQOL in every domain of the SF-36 when compared with GERD-NNS (P < 0.05 for all SF-36 scores), with clinically meaningful differences (defined as a ≥5 point difference17, 18) noted in four of eight domains. These findings are consistent with previously published studies that have found a similar impact of GERD-FNS on HRQOL.1 In particular, we found that the differences in HRQOL scores between GERD-FNS and GERD-NNS were most pronounced in the domains of physical and emotional role function, similar to findings reported by Farup et al.1 We also note that HRQOL appeared to further deteriorate with each additional night per week with symptoms. Although causality cannot be determined through a cross-sectional design, one might speculate that even partial symptom control of nocturnal symptoms can improve HRQOL.
Fourthly, in assessing supra-oesophageal symptoms potentially attributable to GERD, we observed that the proportion of GERD cases reporting supra-oesophageal symptoms was comparable with previous reports.2, 4 Additionally, our analysis revealed that supra-oesophageal symptoms were more common and more severe among participants with GERD-FNS compared with GERD-NNS cases, particularly globus sensation and choking. Furthermore, to our knowledge we are the first to report that supra-oesophageal symptoms among GERD-FNS cases were not only more common at night, but also more common during the day when compared with GERD-NNS cases. This suggests that potential acid exposure of the upper airways while supine at night may have lingering effects that persist even during the day.
There are several limitations to our study. First, our use of an Internet population and selection of well-defined symptomatic cases may limit generalizability to the entire population. However, it should be emphasized that our study was not intended to be a prevalence study, but rather to enable the quantification and subsequent comparison of work productivity loss, sleep impairment, daytime sleepiness and HRQOL impairment among employed individuals with GERD-FNS vs. GERD-NNS and vs. non-GERD controls. In addition, SF-36 scores for non-GERD controls were fairly consistent with US population norms and thus help to support the extrapolation of findings from this Internet sample. Secondly, recall and responder bias may affect interpretation of results, although we have no reason to suspect that this bias was different among the case or control groups. Thirdly, work productivity was assessed using a self-reported instrument without objective, third party validation. However, we were interested in between-group comparisons (GERD-FNS vs. GERD-NNS) and there is no reason to suspect any systematic differences in self-reporting between study groups. Fourthly, although we used the well-established generic SF-36 to measure HRQOL, the use of a GERD-specific HRQOL instrument might have been more sensitive for between-group comparisons of GERD-FNS and GERD-NNS. We selected a general tool in order to perform comparisons between cases and controls, for which a GERD-specific tool would not be appropriate. However, even with the generic instrument we were still able to find significant differences between GERD subgroups. Finally, we observed that individuals with GERD had more concurrent medical conditions than did non-GERD controls. This raises the possibility that sleep and/or HRQOL impairment in GERD sufferers may be due to a higher prevalence of comorbid conditions; for example, anxiety, chronic back pain and headache and could each conceivably contribute to sleep impairment and/or poor HRQOL. However, the prevalence of sleep complaints and HRQOL scores among respondents in our sample is similar to those reported by others,1, 4 even though our study was not intended to be a prevalence study. Furthermore, among GERD cases, we specifically stratified the aetiology of sleep disruption and work productivity loss due to health-related problems (in general) and impairment expressly due to symptoms of GERD. This allowed us to discern differences related specifically to GERD in an attempt to obviate confounding effects. Finally, except for depression, there were no differences in comorbidities between GERD-FNS and GERD-NNS cases, making between-group comparisons among these subgroups more reliable.
Despite these limitations, our study is unique in that it shows that frequent nocturnal symptoms of GERD are common among the working population and are associated with significantly reduced work productivity, sleep impairment and daytime sleepiness. This is a logical association, in which we have distinguished GERD-specific symptoms as the primary reason for sleep and productivity impairment in those patients who suffer from nocturnal symptoms at least twice weekly. The data also reveal an apparent trend between each additional night of symptoms and worsening HRQOL and WPSs. We used standardized and well-established instruments to assess work productivity, daytime sleepiness and HRQOL. Furthermore, in reporting work productivity loss, we were able to distinguish productivity impairment because of all health problems from GERD symptoms specifically, thus potentially controlling for the confounding impact of comorbidities found to be more prevalent among the GERD population.
Our study adds to the growing body of literature on the individual and societal burden of GERD by further helping to define the scope and significance of nocturnal symptoms, including their considerable economic and personal impact on work productivity, sleep and HRQOL. These findings help raise clinician awareness of the underappreciated effects of nocturnal GERD. Improved awareness and understanding of these manifestations should increase recognition of this common condition and thus help to minimize the overall burden of GERD to society.