A study of two generic health-related quality of life questionnaires—Nottingham Health Profile and Short-Form 36 Health Survey—and of coping in patients with sensory hyperreactivity

Sensory hyperreactivity (SHR) was found to be one explanation for airway symptoms induced by chemicals and scents. An objective test method called the capsaicin inhalation cough test and a questionnaire, the Chemical Sensitivity Scale for Sensory Hyperreactivity (CSS-SHR) have been developed to identify patients with SHR, and a high CSS-SHR score is directly related to capsaicin sensitivity [1, 2]. The symptoms of SHR often mimic asthma and/or allergy, but in most cases asthma and allergy tests are negative, and asthma or allergy medication has no effect. The most common symptoms reported by the patients are cough, heavy breathing, difficulty getting air, chest weight, phlegm, hoarseness, stuffy nose, and eye irritation. Some patients also reported more general symptoms such as sweating, dizziness, and headache. Common trigger factors are perfume, flowers, coloured paints, cigarette smoke, and car exhaust fumes, as well as cold air and exercise [3]. More than 6% of the adult population in Sweden has been estimated to have SHR, where the SHR diagnosis was based on a high CSS-SHR score in combination with a positive reaction to the capsaicin inhalation cough test [2].

Health-related quality of life (HRQOL) is a measure of how diseases and symptoms affect health, well-being, and the ability to function in daily life. It includes several dimensions: physical function, role function, e.g., work, home management, social function, psychological function, and general well-being [4]. HRQOL is measured by means of standardized questionnaires, which can be generic or disease-specific. Generic instruments cover a wide range of dimensions and are applicable in a wide variety of conditions. Disease-specific instruments, on the other hand, are designed for a particular patient population. The choice of instrument depends on the approach of the study, and it is important to use instruments that are both reproducible and valid [5]. Generic HRQOL instruments need to satisfy different criteria to be suitable for measuring health outcomes in clinical settings and research. One important criterion is that the instrument should be validated (assessed to ensure it measures what it purports to measure). One aspect of validity refers to construct validity (the ability of an instrument to distinguish between known groups). Another important characteristic is reliability (the degree to which an instrument is free from random error and all items measure the same underlying attribute). Further the instrument must be acceptable to patients, and quick and easy to use [6]. The Nottingham Health Profile (NHP) and the Short-Form 36 Health Survey (SF-36) are both generic instruments that address multidimensional aspects of HRQOL [7].

The NHP questionnaire has been used in several studies of chronic illnesses and conditions [8, 9]. The questionnaire was developed in 1980 at Nottingham University (UK) for measuring subjective health status [10]. Some limitations have been shown with regard to sensitivity. Patients with milder symptoms tend to score zero (no problems) or near to zero, and the questionnaire seems, therefore, to be unsuitable for use in examining improvements [11]. The SF-36 questionnaire was developed 10 years later from a questionnaire known as the Medical Outcome Study General Health Survey Instrument [12]. It has also been used in several studies of various chronic illnesses and conditions [8, 9, 13]. A limitation has been found in the bodily pain dimension in SF-36; it only correlates moderately to a pain scale that quantifies pain severity in patients with hip and knee osteoarthritis [14].

Two previous studies, which used the NHP, have described the HRQOL in patients with SHR [3, 15]. The condition has great influence on several aspects of daily life and the reduced HRQOL did not change during a five-year period [3]. Millqvist el al. showed that patients with SHR with reduced HRQOL were more sensitive to inhaled capsaicin [15]. Using a qualitative approach, Larsson et al. studied a group of patients with SHR and how they handle their problems. The patients felt that there was a lack of understanding from others, felt limitations in daily life and were afraid that the symptoms would indicate a problem that would become a serious disease [16]. Söderholm et al. reported similar results in patients with SHR in regard to their limitation in participating in society and lack of understanding from others [17]. Similar results have been found in patients with chemical sensitivity [also called multiple chemical sensitivity (MCS)]; the results showed a lack of access regarding education, use of public transportation, visits to restaurants, movies, friends, medical care, and problems at work [18‐20]. Further, according to Lipson, people have difficulties living with MCS. They have to face social, attitudinal, and logistical barriers. Social suffering increased for people with MCS because their relationships with family, friends, school or work, and physicians were negatively affected [21].

When people become patients, they enter a stressful situation. Coping is the response that aims to reduce the level of stress. Coping is an attempt to manage situations that produce discomfort, and it is a function of both the environment and the individual’s cognitive appraisal of the situation. According to this theory, the individual and the situation cannot be separated: coping is not outcome dependent; rather it is simply the attempt to manage the situation [22]. The Jalowiec Coping Scale-60 (JCS-60) was developed in 1987 to measure the process of coping [23]. It has been used in several studies in different conditions [24, 25], and studies show that women may use different kinds of coping strategies than men [26, 27]. Depending on their function, coping strategies can be classified in two major categories. One is problem-focused, in which the patient deals directly with the problem, e.g. information, seeking, and goal setting. The other is emotion-focused coping, in which the patient deals with the emotions associated with the stress, e.g., worry or depression. According to Lazarus, in Western culture there is a strong tendency to regard problem-focused coping as being more successful and effective than emotive coping [22].

Nordin et al. studied coping strategies in a group of patients who considered themselves intolerant to odorous/pungent chemicals. The most commonly used and effective coping strategies were avoiding odorous environments, and asking people to limit their use of odorous substances. Other strategies were to accept the situation and reprioritize how important things were [28]. Patients with asthma-like symptoms describe having similar symptoms and trigger factors as SHR-patients. Ringsberg et al. studied the lives of a group of female patients with asthma-like symptoms. The patients had few coping strategies; they experienced social isolation and distress and a feeling of ‘walking around in circles’ [29]. A study with problem-based learning in patients with asthma-like symptoms showed that the participants learned to use new coping strategies, could describe the disorder in words, and had their self-confidence increase [30]. Larsson et al. showed that patients with SHR cope with their symptoms by avoiding situations that they cannot tolerate. Another way they managed difficult situations was by disparaging the symptoms or to simply denying them [16].

Little is known about HRQOL and which of the two generic instruments, the NHP or the SF-36, is more suitable for measuring HRQOL in patients with SHR. Further, little is known about coping strategies among patients with SHR. In addition, little is known about gender differences and differences between normative data in HRQOL and coping among these patients. These issues can, however, be examined using established questionnaires.

The aims of the present study of patients with SHR were (1) to compare two generic quality-of-life questionnaires, the NHP and the SF-36, regarding their suitability (in respect of floor effects, ceiling effects, validity and reliability), and acceptability (assessed by using the completion rate as an indicator) as outcome measures of HRQOL; (2) to evaluate how these patients cope with the illness; (3) to assess whether there are differences between women and men with respect to HRQOL and coping, and (4) to assess whether there are differences between patients and normative data with respect to HRQOL and coping.

The main results in the present study can be summarized as follows. First, the results indicate that the SF-36 scores were less skewed and more homogeneously distributed than the NHP scores. The SF-36 showed less floor and ceiling effects compared with the NHP. The SF-36 was also better for discriminating between patients with high and low CSS-SHR scores with regard to role limitations due to psychical problems and general health. The reliability standard for both questionnaires was satisfactory. No gender differences in HRQOL were measured with the two instruments. Second, the most commonly used coping styles were optimistic, self-reliant, and confrontational coping. Women used optimistic coping significantly more than men. Third, patients with SHR had significantly higher impairment in several dimension of HRQOL compared with the reference group. Further, the patients used optimistic and confrontational coping more and emotive coping less, compared with the reference group.

Both the NHP and the SF-36 have been compared in several studies in patients with different diseases [8, 9]. The NHP has been used in patients with SHR [3, 15], but the SF-36 has never been used in this group of patients. To assess the utility of these instruments as a general outcome measure of HRQOL, different criteria have to be taken into consideration. It has to be quick and easy to use. Both HRQOL questionnaires fulfilled these criteria, taking about 10 min to complete. The instrument should also be acceptable to respondents with few missing values, which was indicated with the high response rate of 72% in the present study, and showing only one or few missing values among the participants in both questionnaires. Further, the availability and the cost of using a questionnaire are also important factors. Some advantages with the NHP are that it is readily available and inexpensive to use. The SF-36, on the other hand, is strictly copyrighted, and is rather expensive to administer because of a user fee [45].

The patients NHP and SF-36 scores differed to the same extent from the reference values, with significantly lower scores (more difficulties) in comparable domains: emotional reactions/mental health, energy/vitality, physical mobility/functioning, and pain/bodily pain. This is in line with a study in patients with SHR and in a study of long-term survivors after a myocardial infarction [15, 46]. In social isolation/functioning, the results were different, with NHP scores similar to normative data and SF-36 scores significantly lower. The result in social isolation is in contrast to a longitudinal study in patients with SHR, showing a greater impairment in social isolation, compared with reference values [3]. There were no differences from reference values in sleep, the other NHP score. All other SF-36 scores were also lower and differed significantly from reference values, social functioning, role-physical, role-emotional, and general health.

The present NHP results showed a higher prevalence of ceiling effect (indicating best possible quality of life) in all dimensions compared with the SF-36 results, but also a higher prevalence of floor effects in energy (indicating lowest possible quality of life). Otherwise, there were minor floor effects in both the NHP and the SF-36. This is in accordance with other studies in patients with chronic limb ischemia [8, 47] and in patients with chronic obstructive disease [48], which showed fewer ceiling and floor effects in the SF-36 compared with the NHP. The advantages with the SF-36 may depend on each item having different possible scores, whereas the NHP items are dichotomous with only a yes/no alternative, providing more possibilities for results at the extreme ends of both good and ill health. To use a score with only a yes/no alternative may also make it difficult to show improvement over time. The findings of Chronbach’s coefficient α values of ≥ 0.70 in all but one dimensions of HRQOL implies good internal consistency for both questionnaires in accordance with earlier findings [8, 47], but the SF-36 seems more preferable because it has the highest α values.

As mentioned, the CSS-SHR questionnaire can be used to quantify self-reported sensitivity to chemicals and scents in the course of daily activities [32]. Our results showed that patients with high CSS-SHR score reported significantly more problems with role limitations due to psychical problems and general health than those with low CSS-SHR score, measured with the SF-36. This is in line with Brown et al., showing the SF-36 to be more sensitive than the NHP in detecting the impact of breathlessness in patients after a myocardial infarction [46]. In contrast, Wann-Hansson et al. demonstrated that patients with critical leg ischemia had more problems with pain and physical mobility before revascularization than those with intermittent claudication, measured with the NHP [8]. Similar results have been found in patients with chronic limb ischemia, showing NHP to be more sensitive in detecting problems with pain and psychical mobility [47]. Nevertheless, Prieto et al. found that both instruments are similar in discriminating among different levels of respiratory impairment [48]. However, the SF-36 seems to have more validity in discriminating among levels of chemical sensitivity in patients with SHR. The SF-36 results are less skewed and more homogeneously distributed, which may suggest that it is more sensitive to explain HRQOL in patients with SHR, with respect to psychical problems and general health.

The patients in the present study used optimistic and confrontational coping significantly more and emotive coping significantly less often than the reference values. This is in line with the results of Lindqvist et al., who found that people with kidney transplants used optimistic coping significantly more and emotive coping significantly less often than the general population [41]. Further, the most frequently used coping styles among the patients were optimistic, self-reliant and confrontational. The two least used coping styles were palliative and emotive. This is in line with results in patients on continuous ambulatory peritoneal dialysis [40], people with kidney transplants [41], and patients with myocardial infarction (MI) [13]. Kristofferzon et al. found that over a 12-month period the most used coping methods after an MI were optimistic, self-reliant and confrontational and the least used methods were palliative and emotive [25]. The Chronbach’s coefficient α values of ≥ 0.70 was only found in four out of eight coping styles (optimistic, self-reliant, confrontational and evasive). The results are in accordance with a Swedish population study [26] and in patients after an MI [13].

The current findings showed that both the NHP and the SF-36 were reliable instruments; but the results suggest that the SF-36 is a more sensitive method than the NHP to elucidate HRQOL in patients with SHR. Patients with SHR experienced a lower HRQOL, and used more optimistic and confrontational coping, compared with normative data. They followed the Western tradition of preferring problem-focused coping strategies to palliative and emotive strategies.