Rheumatic diseases and sexuality: Disease impact and self-management strategies




To explore how intimate relationships and sexuality are influenced by rheumatic diseases and to describe self-management strategies used to manage disease consequences.


To ensure that data were grounded in patients' language and experiences, individual and focus group interviews were conducted. Purposeful sampling was used to ensure variation in age, sex, disease duration, diagnosis, and marital status among the informants. Participants were men and women ages 18 years or older, were diagnosed with inflammatory rheumatic disease by a rheumatologist, and had a disease duration of ≥2 years.


The mean age of the 23 participants was 44 years, the mean disease duration was 13.6 years, and the mean ± SD modified Health Assessment Questionnaire score was 1.58 ± 0.46. Four key themes summarized the main issues described by the informants: between disease and normality, relational aspects, disease-related sexual challenges, and self-management strategies. The results reveal that the disease constituted a disruption in life, requiring a new orientation of sexual identity and relationship. Participants' experiences of sexuality went beyond specific sexual activity, including aspects such as body image and relational issues, illustrating a multidimensional perception of sexuality. A large inter- and intrapersonal variety of impact and a wide range of management strategies were reported.


This study shows that sexuality is a vital area of life for people living with arthritis. It is a source of physical pleasure and intimacy with their partner, but may cause anxiety and distress when affected by rheumatic disease. However, various self-management strategies are applied to enhance intimate relationships and sexual activity. Knowledge and openness concerning sexual issues need to be emphasized as part of the competence of health professionals and researchers.


Chronic rheumatic diseases are characterized by fatigue, pain, stiffness, and reduced physical function. These disease features may lead to depression and an altered body image, which again may have a negative impact on sexual life in terms of reduced desire and pleasure, pain during intercourse, erectile dysfunction, and distortion of intimate relationships (1–9).

Human sexuality can be defined as how people experience the erotic and express themselves as sexual beings, and has biologic, physical, and emotional aspects (10). Population studies have demonstrated a strong relationship between quality of life and sexual function and satisfaction (11, 12).

The prevalence of sexual problems in rheumatic diseases varies between 27% and 67% (2, 13–17). Compared to a reference group of healthy individuals, women with rheumatoid arthritis (RA) reported less satisfaction with sexual life two years after disease onset, and women with longstanding disease reported even lower levels of satisfaction (18). In another study of patients with rheumatic disease and their partners, greater arthritis pain was related to greater sexual dissatisfaction for spouses, but not for patients (19). Therefore, sexual health seems to deteriorate over time and have implications for those with disease as well as their partners.

In spite of the high prevalence and great impact of sexual problems, sexuality in rheumatic diseases has received scant attention. Furthermore, previous research has not taken into consideration the complex and multifaceted aspects of sexuality in the context of rheumatic disease, as the focus has primarily been on sexual problems (20).

The aims of this study were to explore how intimate relationships and sexuality are influenced by rheumatic diseases and to describe self-management strategies used to manage disease consequences.


Study design.

To ensure that data were grounded in the patients' language and experiences, individual and focus group interviews were conducted. The study was approved by the Regional Committee for Medical Research Ethics.


Purposeful sampling was used to ensure variation in age, sex, disease duration, diagnosis, and marital status among the informants. Participants were identified among patients at a rheumatology clinic in Oslo and requested to participate by one of the authors (YH) or by a staff member. Participants were men and women ages 18 years or older diagnosed by a rheumatologist as having RA, ankylosing spondylitis, psoriatic arthritis, or juvenile idiopathic arthritis. Disease duration had to be ≥2 years. Forty-nine patients were invited and 29 accepted to participate. Of these, 5 patients were not able to meet for an interview at a scheduled time; therefore, 24 persons completed interviews.

Data collection.

The interview guide was informed by a literature review and repeated discussions with a resource group, including 2 men and 3 women with RA or ankylosing spondylitis, and a nurse and a physiotherapist, both female. The group contributed relevant topics and sensitive formulation of questions (Table 1). Interviewers followed up the participants' responses with further probing questions, as appropriate.

Table 1. Interview guide
DemographicsAge, sex, marital status, diagnosis, symptoms
Introductory questionsDo you experience that the disease has affected your daily life, your relationship, and/or your sexual life in any way?
MedicationExperiences with side effects related to sexual life?
Body image and appearanceExperiences with visible changes on the body?
Experiences with changed physical function?
Intimate relationshipsPerceptions of the disease as affecting (positively/negatively) the possibility to gain or wanting to have a partner
Interactions in intimate relationshipsExperiences of impact of the disease on relationship?
Physical functionCommunication: timing and content
Things you want to do during sex which you are not able to?
Experiences with handling the effect of the disease on sexual life and relationship?

Nineteen semistructured, in-depth interviews were conducted by one of the authors (YH), and a senior researcher (ES) conducted one focus group interview with 3 men and one focus group with 3 women. One female informant participated in both an individual and a focus group interview, and one interview was excluded due to poor data quality; therefore, analyses are based on responses from 23 patients. All interviews took place in a private, neutral meeting room at the hospital and lasted 1–2 hours for the in-depth interviews and 2.5 hours for the focus group interviews.

Following the interview, each informant filled out a questionnaire concerning personal and disease-related variables. For the purpose of describing the sample, physical function was assessed by the modified Health Assessment Questionnaire (M-HAQ; scale range 1–4, where 4 = worst score) (21).


All interviews were audio taped and thereafter transcribed verbatim and anonymized by two trained secretaries. The transcripts were checked against the audio tapes. The QSR International NVivo data program for qualitative analysis was used for coding and systemizing.

To validate the process of analyzing the data, one of the authors and a senior researcher (YH and ES, respectively) independently reviewed and identified preliminary themes based on 5 transcripts. Transcripts were thereafter thematically analyzed by the one of the authors (YH), following a descriptive phenomenological approach (22, 23). Coding, thematic structure, and interpretation of the material were further discussed with the resource group and thereafter with a team of qualitative researchers to ensure that all relevant topics had been identified and alternative interpretations were taken into consideration (Figure 1).

Figure 1.

Strategy for collection and management of data.


Characteristics of the participants.

The mean age of the 23 participants was 44 years, 2 were ages >60 years, and 3 were ages <35 years. The mean disease duration was 13.6 years and the mean ± SD M-HAQ score was 1.58 ± 0.46. Demographic and disease-related characteristics are further shown in Table 2.

Table 2. Demographic and disease-related characteristics of the participants*
  • *

    M-HAQ = modified Health Assessment Questionnaire (range 1–4, where 4 = worst score).

Personal factors 
 Age, mean ± SD (range) years44.2 ± 10.5 (29–66)
 Male sex, %57
 Diagnosis, no. (%) 
  Rheumatoid arthritis11 (48)
  Ankylosing spondylitis7 (30)
  Psoriatic arthritis4 (17)
  Juvenile idiopathic arthritis1 (4)
 Marital status, no. (%) 
  Married/cohabiting/relationship19 (83)
  Single4 (17)
Disease-related factors 
 Disease duration, mean ± SD (range) years13.6 ± 10.2 (2–34)
 M-HAQ score, mean ± SD1.58 ± 0.46

The results are shown according to 4 key themes, summarizing the main issues described by the informants (Table 3). Although the themes capture different aspects of sexuality, they are also interrelated and overlap.

Table 3. The 4 main themes described by the informants shown with illustrating quotes
ThemesIllustrating quotes
1. Between disease and normality 
 New orientation/renegotiation“The only thing I needed was a shoulder to cry on and an arm that cared and didn't mind. Our exciting sex life turned into more of a deeply caring relationship, which was really great” (woman, age 62 years)
 Intrapersonal variance of impact“Fluctuations in the disease and symptoms restrict my sex life. Sometimes it poses a problem, very often it doesn't. It's very up and down – there's no pattern” (woman, age 43 years)
 Comparison with able bodied“Sexual life is so incredibly susceptible to everything, it's so much in life that affect; stress, education, and concerns. So my experience is that many are concerned that they do not want too much put on the disease. There is so much in life in general that affect sexuality – okay, there are some drawbacks with it (the disease), but we experience many of the same stressors as healthy people do” (woman, age 29 years)
 Body image“It's not always easy being in my body then, and that means I probably have a slightly different relationship to my body than other people. It's about pain, living with pain, and it's about functionality – I become disabled. And then my body is not an instrument for dance and joy, but an obstacle” (woman, age 29 years)
2. Relational aspects 
 Understanding“It had a huge impact on our sex life that he never seemed to understand that I was exhausted or in pain until I couldn't sit down, go to the toilet or walk. Then he understood, and that hurt my feelings” (woman, age 43 years)
 Accept“Everything depends on the partner and whether he is confident enough. Some people mind about some things, and other people mind about other things, so it's a case of finding someone who doesn't mind too much” (woman, age 44 years)
 Meeting a partner“It's not easy to find a man (…) I often think that nobody could love me the way I look now, because I look awful, don't I?” (woman, age 48 years)
3. Challenges in sexual life 
 Reduced/loss of desire“The disease has had a huge impact on my sex life. Not in terms of physical problems, but sex drive. It's really reduced” (man, age 56 years)
 Sex less in focus“When you can hardly move and you have pain in your entire body, sex isn't exactly what's on your mind” (woman, age 40 years)
 Interruption of sexual activity“If there is a soft bed and I suddenly wiggle a little wrongly, it's all over. We need to quit immediately. Because then it hurts somewhere and then I can't get it up” (man, age 30 years)
 Fluctuations in sexual life“In bad periods with a lot of activity, I feel rotten inside and then sex is not foremost in my mind. I feel very unattractive and tend to say no thanks” (woman, age 35 years)
 Erectile dysfunction“Getting an erection – everyone knows it's a really touchy area for men. I didn't think I would care about it so much, but I did. I would not have been so upset if it had been because my hip was so bad or my arm was like that” (man, age 44 years)
4. Self-management strategies 
 Activity/passivity“If I am in a lot of pain, it's better that I am in control, that I take the lead. Then we do different things or use different positions, which might mean that I am on top or that I make sure I don't get hit or bumped. It is important that I have control over the movements” (woman, age 29 years)
“It's irritating (being passive). Feeling that you can't do exactly what you want for yourself or to make it best for both of us” (man, age 30 years)
 Communication/silence“I don't say much and I hide a lot because I feel it is bad enough for him that I am so sick and I don't want to burden him more by talking about it all the time” (woman, age 40 years)
 Stretching“I have pushed myself. Even if I was exhausted, I have made a really big effort. I don't want all the reasons he is with me to disappear” (woman, age 44 years)

Between disease and normality.

The majority of participants expressed that the rheumatic disease constituted a disruption in life, a discontinuation of self, and of what the future was expected to be. The disease created new premises for the body, and hence for sexuality, leading to their questioning how to cope with the intimate aspects of life. For many informants, this was a lifelong process due to the fluctuating and progressive character of their disease. A core theme was to what degree one should bring the disease into the sexual and private sphere. The informants described a continuous inner consideration concerning when and in which settings and relationships it was legitimate to be sick. One informant expressed it as follows: “… the fear of being abnormal in so many ways, of being sick on so many levels” (woman, age 44 years). Another participant stated: “I do not want to talk about it in all settings” (woman, age 29 years). Most informants were reluctant to assume a sick role in the intimate sphere and therefore found it difficult to communicate about sexual issues with their partner.

Furthermore, many informants described that the disease constituted a change in their body image as a result of changes in their physical appearance and loss of physical competence and function: “And then my body is not an instrument for dance and joy, but an obstacle” (woman, age 29 years).

For some of the female informants, their altered body image also affected their desire for sexual intimacy. This was mostly due to changes in physical appearance, which again reduced their sense of being attractive. One woman with psoriatic arthritis stated that “The psoriasis rash has been a bigger obstacle (in sex life, than the pain) because I find it so disgusting” (woman, age 44 years). She experienced the psoriatic rash as the most limiting factor on sexuality above the pain, indicating that it is not necessarily the strongest rheumatic symptoms of disease that have the greatest impact on sexual life. However, a few women specifically stated that physical ability was more important than appearance, thus attaching less importance to attractiveness.

The men also talked about changes in appearance. Although the youngest male informants attached importance to their appearance, the majority of the men did not regard themselves as less attractive and they were generally less worried about this issue.

There was a large variance in the experiences and perceptions of how and to what extent the disease affected sexuality. Some informants reflected on whether or not their own sexual life and challenges were different from what other people experience. While some expressed uncertainty, others did not perceive their challenges to be any different from those of their friends and colleagues. One man said that “My able-bodied colleagues have many of the same problems as me: I'm not in the mood, I can't be bothered, there's no time or no opportunity” (man, age 44 years). Some of the female participants also questioned whether their perceived sexual challenges were caused by their disease or were common sex differences experienced by most women. Therefore, placing sexual challenges in the context of normal everyday life for some seemed to ease the perceived burden of disease on sexual activity.

Relational aspects.

The informants reported that their perceived disease impact on sexuality was influenced by the partner's degree of understanding, empathy, and acceptance.

The fluctuating disease course and invisible symptoms characterizing rheumatic diseases were identified as a common challenge, leading to unpredictable physical ability and desire in sexual life. This could be difficult to understand for the partner, resulting in increased sexual-related conflicts. For some female informants, a lack of understanding led to reticence from physical contact.

By contrast, some informants experienced acceptance from their partner and underlined that a shared understanding of the fluctuating nature of the disease could increase flexibility and improve communication. Both partners had the opportunity to adjust sexual activity according to desire and condition, and guiding of the partner during the sexual act was facilitated. Even if the male informants also appreciated understanding from their partner, only one expressed that this had had any influence on their sexual life or intimate relationships.

The importance of acceptance related to physical deformities was verbalized by both male and female informants. They described how changed physical appearance could significantly affect body image, self-esteem, and sexual life, and that their partner's acceptance and feedback could help counteract this negative effect. A sex difference was noticeable in this area, as some of the female informants described themselves as being less susceptible to positive external evaluation, while none of the men addressed this issue.

Informants perceived that the disease affected their opportunity to meet a partner. Meeting a new partner was most likely during periods of remission, due to more energy to be social and an increased feeling of attractiveness. However, some informants were worried that meeting a partner in a good period might give a false impression of the sexual life.

A perceived reduced value as a partner was related to unpredictability of future health, energy for social activities, and reduced attractiveness caused by physical deformities. Some informants also reported that they had avoided pursuing a new relationship because they were afraid of not having the energy to meet the wide range of requirements related to long-term partnership or starting a family.

Disease-related sexual challenges.

The informants described a wide range of disease-related challenges influencing sexual activity. There was, however, interpersonal variance in influence, as some participants expressed that the disease did not impact sexual life, whereas others said it had more or less ruined their sexual life. Furthermore, participants described intrapersonal variance related to fluctuations in disease course and symptoms.

Loss of or reduced desire.

The most frequent and intrusive challenge, described by all but 3 of the informants, was a loss of or reduction in desire, constituting a massive strain on sexual life. This challenge could be attributed to the disease (such as high disease activity, pain, stiffness, fatigue, and physical impairment), to the treatment (in terms of side effects of medication), to less self-esteem (due to changing appearance), or to a lack of understanding from their partner. For some, the loss of sex drive was more or less permanent; for others, it was periodical. One male participant expressed it as follows: “It's probably the worst thing about the whole affair. Actually. Because you don't feel much of a man” (man, age 56 years).

Sex less in focus.

Some of the informants described sex as being less important, and both male and female informants described a reduced need for sex compared with before disease onset.

Fatigue was the symptom regarded as having the greatest impact on sexual activity and the main reason for sex seeming less important: “The disease takes all your energy. You just don't want to bother (having sex). I never thought like that before. But now, the need for sex is not as strong anymore. It's not that sex is not important; it's just less urgent” (man, age 44 years).

The informants also reported that sex was a lower priority during disease flares. Sexual activity was often reduced or came to a halt in periods of high disease activity, due to a reduced sense of attractiveness or an inability to participate in sexual activity due to physical limitations.

Although many informants stated that new biologic drugs resulted in disease improvement, this improvement did not necessarily translate into an improved sex life, primarily due to continued fatigue.

Restrictions in sexual activity.

Informants described restrictions in movement and positions, as well as finding sex unpleasant or even impossible, due to a psoriatic rash in the genital area, pain, stiffness, and/or joint replacements. Participants knew that certain positions can be painful and may even dislocate joints, such as lying underneath and/or abducting the hips. This knowledge had a direct impact on tempo, movement, and positions in the sexual act. The constant consciousness concerning movements and actions was also experienced as preventing people from surrendering completely to the sexual act, restricting spontaneity, and leading to reduced passion and desire. Furthermore, many participants experienced pain and stiffness in the days following sex. However, while previous painful experiences led to anxiety and cautiousness for some of the participants, others stated that such experiences had no influence on their current sex life.

Interruption of sexual intercourse.

Another major challenge reported by participants was the fear of having to interrupt the intercourse. One female informant elaborated on her worries and considerations before and during sex, due to the unpredictability of symptoms, pain, and mobility: “I have been forced to interrupt sex sometimes. (…) It's always in the back of my mind; will I be able to carry it through? I worry that it will hurt his feelings or make me feel bad, because I have initiated something that I couldn't follow through on” (woman, age 29 years). Therefore, for some of the participants, initiating or consenting to sexual activity implied an obligation and mental pressure to complete the act.

Erectile dysfunction.

Some of the male informants experienced erectile dysfunction, which was described as a shock and a threat to their sense of masculinity. While one man related this to intense pain during sexual activity, the other perceived it as a side effect of medication. None of the participants had received any information about the risk of erectile dysfunction as a side effect of medication, which again increased the anxiety and stress related to this issue.

Self-management strategies.

The perceived disease impact on sexuality varied considerably among participants. Therefore, some grieved the reduced need for sex, while others had come to terms with the situation and did not miss a higher level of sexual activity. Furthermore, the inability to accomplish sex was unproblematic for some if the situation was not persistent, while others found it difficult to cope with.

The informants described a number of self-management strategies, including postponing sexual activity until flares had passed; ignoring restrictions; adapting positions and movements; using alternative locations, painkillers, or pillows; initiating less strenuous sexual activity; having sex despite a lack of desire; and being creative during the sexual act: “I hurt my shoulder a few years ago, so then it's best to be underneath. Now it's a bit hard to stand above because of my knee. But I can lie on my side, or behind. You can stand up, use a table” (man, age 44 years). Therefore, flexibility and creativity appear to be important in order to have a satisfying sexual life in spite of functional limitations.

Participants described consciously taking an active or passive role in the sexual act as a self-management strategy. Some deliberately took an active role in order to avoid sudden, unexpected movements by their partner and thereby limit pain.

Nevertheless, being passive was the most frequently cited strategy to control symptoms during the sexual act. However, this strategy was in general perceived as negative, limiting pleasure and creativity, and sometimes misinterpreted by the partner as a lack of desire: “My experience is that you really want to be active, but you end up with being passive, and that's not very exciting, is it? It does something with your self-esteem or the sense of being attractive…” (woman, age 37 years). Many informants stressed that a satisfactory sexual encounter was dependent upon interaction and agreement between partners.

Choosing to be silent or to communicate about difficulties in sexual life with the partner was also a strategy described by the informants, with being silent as the most frequently reported. In general, the informants described a dilemma related to communication concerning the disease. While silence might result in loneliness, too much talking about disease problems could place a strain on close relationships. However, a lack of communication also constituted an additional burden on sexual life, as it resulted in preservation of conflicts and misunderstandings related to impact of disease.

Some female participants described a strategy they termed “stretching” or pushing themselves, meaning having sex despite reduced desire or energy. Reasons given for pushing themselves included consideration for the partner and a wish to be spared from the burden of giving their partner a poor sex life. Some also stated a general fear of being left by their partner, and that a lack of sexual intimacy would give their partner an additional reason to leave. Yet others said that they did not want the sexual area to be affected by the disease. One woman expressed it follows: “…things have to be pretty bad for me to say I'm in too much pain and not in the mood. (…) I really don't want to be a dull, sick woman who doesn't have sex” (woman, age 29 years).

It is also important to note that some participants used sexual activity as a positive self-management strategy, as they experienced pain relief, loss of negative focus, and increased tolerance when they were sexually excited and/or active. Additionally, pain was not necessarily perceived as restricting sexual activity, but could instead be used to guide movements. Most informants also stated that they usually enjoyed the sexual activity when first initiated, and that sexual activity could create and sustain a good life and relationship.


We have previously shown in a quantitative study that patients with RA frequently report impact of disease on sexual activity (14). These findings inspired us to explore the qualitative nature of this impact, as well as other aspects of sexuality in the context of rheumatic disease. The current study is one of the first to explore how patients experience and manage the impact of rheumatic disease on sexuality. In particular, the results reveal that the disease constituted a disruption in their life, which for most informants required a new orientation of sexual identity and relationship. Participants' experiences of sexuality went beyond specific sexual activity, including aspects such as body image and relational issues, thereby illustrating a multidimensional perception of sexuality. The study also demonstrated a large inter- and intrapersonal variety of impact, as informants' descriptions ranged from no perceived impact to severe impact, and with considerable individual fluctuations. Participants reported a wide range of self-management strategies, and some used sexual activity as a positive strategy to relieve pain and strengthen the relationship with their partner.

Many informants reflected on whether their perceived sexual problems were within a normal spectrum or caused by their rheumatic disease. Studies comparing the prevalence of sexual dysfunction in people with arthritis with control groups without arthritis are scarce, and the results are conflicting. In a study of 169 patients with rheumatic disease and 130 controls, the patients experienced a greater loss of sexual satisfaction over time, but the two groups reported similar reductions in frequency of intercourse and were comparably satisfied with their current sexual adjustment (7). Therefore, future studies should explore sexual dysfunction in larger populations to generate knowledge not only of sexual problems in general, but also about the reasons for and consequences of such problems, as well as strategies to manage sexual dysfunction.

In line with previous research, reduced or loss of sexual desire was the problem most frequently reported by participants (2, 3, 8, 13). Fatigue was the symptom that had the greatest impact on sexual activity and the main reason for sex to be less in focus. The innate fluctuations of the rheumatic disease further generated a general unpredictability, which for some of the informants led to reluctance to initiate or engage in intimate relationships. Even if new and effective medical treatment often leads to improved health status, informants reported a lack of improvement in sexuality, primarily due to unchanged fatigue.

Studies evaluating the effect of expensive forms of treatment should focus on outcomes that are important to patients, but at present sexual functioning is still not part of frequently used outcome measures used to assess function or quality of life. Also, erectile dysfunction as a possible side effect of medication should be given more attention. Therefore, further research regarding the effects of drug therapy on sexual life is warranted, and information concerning drug use needs to be improved (24).

It is a paradox that while sexual matters are increasingly “hyped” in the media, communicating on sexual expectations and needs still seems to be challenging for patients, health professionals, and researchers (2, 24, 25).

In a British study, poor communication between patients and health professionals was reported as a major problem, with patients being reluctant to approach health professionals and vice versa (2). Furthermore, in an audit of adolescents with juvenile idiopathic arthritis, documentation of sexual health was found in only 11.4% of case notes (25). This indicates that health care providers are uncertain about how to include sexual issues in their professional role.

Additional education may be one way to improve health professionals' competence in sexual health. However, as the authors of the newly published Recognition Model emphasize, health professionals can also rely on their existing skills when responding to direct or indirect questions asked by patients concerning sexuality (26). The model further describes 5 stages for addressing sexual concerns: recognizing individuals as sexual beings; providing sensitive, permission-giving strategies; exploring sexual concerns; addressing issues that fit within a team's expertise; and referral, when necessary.

Another recent model, termed “The Good-Enough Sex model for couple sexual satisfaction,” focuses on realistic couple sexual satisfaction as a primary treatment goal. Furthermore, that treatment needs to be individually tailored to each couple, integrating medical, pharmacologic, psychological, and relationship aspects (27). This may include discussing the problems with the partner, exploring different positions, use of analgesics, and exploring alternative methods of sexual expression (28).

A strength of this study was the use of qualitative methods that are suitable to investigate multifaceted phenomena as experienced by people and explore areas with limited knowledge (29). Also, the input from patients and experienced health professionals when designing the study ensured that relevant and important questions were included and sensitively formulated in the interview guide. However, attitudes and norms concerning sexuality vary hugely between cultures, and transference of results beyond the study setting should therefore be done with caution.

In summary, this study shows that sexuality is a vital area of life for people living with arthritis. It is a source of physical pleasure and intimacy with their partner, but may cause anxiety and distress when affected by rheumatic disease. However, various self-management strategies are applied to enhance an intimate relationship and sexual activity. Knowledge and openness concerning sexual issues need to be emphasized as part of the competence of health professionals and researchers.


All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be published. Dr. Dagfinrud had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study conception and design. Helland, Kjeken, Steen, Kvien, Hauge, Dagfinrud.

Acquisition of data. Helland, Steen, Hauge, Dagfinrud.

Analysis and interpretation of data. Helland, Kjeken, Kvien, Hauge, Dagfinrud.