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Occupational Medicine Advance Access originally published online on October 17, 2006
Occupational Medicine 2007 57(1):43-49; doi:10.1093/occmed/kql107
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© The Author 2006. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org

Health complaints and sickness absence in Norway, 1996–2003

Camilla Ihlebaek1, Soren Brage2 and Hege R. Eriksen3

1 Section of Occupational Health and Social Insurance Medicine, Norwegian Back Pain Network, Research Unit, Unifob helse, University of Oslo, Oslo, Norway
2 Section of Occupational Health and Social Insurance Medicine, University of Oslo, Oslo, Norway
3 Department of Education and Health Promotion, Norwegian Back Pain Network, Research Unit, Unifob helse, University of Bergen, Bergen, Norway

Correspondence to: Camilla Ihlebaek, HALOS Unifob, University of Bergen, Christiesgt 13, 5015 Bergen, Norway. e-mail: camilla.ihlebaek{at}psych.uib.no


   Abstract
Top
 Abstract
Introduction
 Methods
 Results
 Discussion
 Conflicts of interest
 References
 
Background From 1996 to 2003, the total number of sickness absence days increased by 65% in Norway.

Aim To investigate if this could be explained by a corresponding increase in the prevalence of self-reported health complaints in the same period.

Methods Representative samples of the Norwegian working population in 1996 (n = 838) and 2003 (n = 637) answered the subjective health complaints (SHC) questionnaire. The single items of the SHC questionnaire were matched with the corresponding sickness absence statistics from the National Insurance Administration in 1996 and 2003.

Results The main finding was a poor concordance between the change in prevalence of health complaints and the change in the prevalence of sickness absence for diagnoses corresponding to these complaints. The prevalence of health complaints in Norway was high and relatively stable from 1996 to 2003. The only complaints that increased in prevalence during the period were allergy and severe asthma. Sickness absence for health complaints, however, showed a general increase. The diagnoses with the largest percentage increase in sickness absence were sleep problems, tiredness, anxiety and palpitation, although the absolute number of individuals with sickness absence for these complaints was small.

Conclusions The increased sickness absence in Norway from 1996 to 2003 cannot be explained by an increase in health complaints in the general population in the same period. The increase in sickness absence is most likely to be explained by multifactorial causes, such as changes in working life and health expectations.

Keywords      Health complaints; Norway; sickness absence


   Introduction
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 Abstract
 Introduction
Methods
 Results
 Discussion
 Conflicts of interest
 References
 
In Norway, the total number of sickness absence days refunded by the National Insurance to employees, civil servants excluded, has increased by 65% from 1996 to 2003. The number of disability pensioners has, in the same period, increased by 26% [1]. Expressed as sickness absence days per days employed, the increase is from 10% to 14% (46%) and the proportion of disability pensioners in the population aged 16–67 years has increased from 8% to 10% (24%) [1]. Musculoskeletal pain, gastrointestinal complaints, tiredness, fatigue and allergic and respiratory complaints are frequent causes for medical consultation [2,3], and general practitioners base their diagnoses on subjective reports in as much as two-thirds of the patients [4]. These health complaints are often unspecific with no findings of significant pathology. The prevalence of health complaints in the general population has been found to be considerable [5–15]. Women report more of these complaints than men do, and there are also age differences in risk of reporting these complaints [6,8–10].

Some health complaints are normal aches of short duration and low intensity, and are a natural part of life. For a large proportion, however, the pains and complaints are substantial and long lasting and might have serious implication for functioning at work. There are no sharp or obvious limits in the distribution of health complaints that separate ‘normal’ and endurable complaints from intolerable complaints [6]. The consequences on daily life and work participation that health complaints might cause will depend upon several individual, social, occupational and psychological factors [16–19].

Health complaints in the general population represent a pool from which cases requiring assistance, medical service and sickness absence develop. It is, therefore, important to follow the development of these complaints. However, little information is available on the stability of the prevalence of health complaints over time. The proportion of individuals in Norway that rates their general health as well is found to increase [20]. This contrasts with the findings that sickness absence and disability pensions are increasing [1].

In this study, we therefore investigated if the prevalence of health complaints has increased from 1996 to 2003, corresponding to increased sickness absence in the same period.


   Methods
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 Abstract
 Introduction
 Methods
Results
 Discussion
 Conflicts of interest
 References
 
During 3 months in spring 1996, 2004 participants in a national survey, interviewed monthly by the opinion poll firm Norwegian Gallup, were asked to participate in the investigation. A standard procedure of computer-assisted telephone interviewing was followed: a sample was drawn randomly, using telephone numbers in proportion to the population in each small municipality, to ensure a representative sample of the adult population (≥15 years). The sample sizes were determined by Norwegian Gallup and were convenience samples. The opinion firm aim for representative samples as they carry out political and commercial opinion polls on a regular basis. The respondent in each household was selected by interviewing the one who had the most recent birthday, with five recalls if not reached. The procedure was repeated until the required sample of ~2000 was obtained. Questionnaires were then distributed by mail and 1240 (62%) answered. In spring 2003, the same opinion firm collected new data on a new sample, during the monthly national omnibus registrations. They followed the same standard procedure as described above although this time the sample goal was ~1000 individuals, and the informants were telephone interviewed directly as a part of the omnibus (n = 1014). Classic response rates for quota sample surveys are not quantifiable since the random sampling is done continuously from a representative population until the quota is reached. It is, however, indicated by other studies that 30–55% of eligible subjects responds at such surveys [21]. The main reasons for not participating are usually lack of time, objections to telephone interview or no particular reason. To enable better agreement with the national sickness benefit register, we included only individuals 16–67 years old who reported themselves to be in part-time or full-time work, reaching a sample size of n = 838 in 1996 (67% of total sample) and n = 637 individuals (62% of total sample) in 2003. No ethical clearance was needed, as all data were made anonymous and untraceable before we received it.

To measure the prevalence of health complaints, we used the subjective health complaints (SHC) inventory [5], which consists of a list of 29 common health complaints. Responders are asked to grade intensity of each complaint on a four-point scale (0 = not at all, 1 = a little, 2 = some, 3 = severe) as experienced last month. Based on factor analysis, sum scores on five dimensions are usually reported [5]: musculoskeletal complaints (headache, neck pain, shoulder pain, pain in arms, pain in upper back, low back pain and leg pain), ‘pseudoneurological’ complaints (extra heartbeats, heat flushes, sleep problems, tiredness, dizziness, anxiety and sadness/depression) (the term ‘pseudoneurology’ was selected since this is the term used in the DSM IV for this cluster of complaints), gastrointestinal complaints (heartburn, stomach discomfort, ulcer/non-ulcer dyspepsia, stomach pain, bloating, diarrhoea and constipation), allergic complaints (asthma, breathing difficulties, eczema, allergies and chest pain) and flu (cold, flu and cough).

In Norway, the sickness compensation system covers 100% of the wage loss from the first day of reported sickness. Self-certification is required for the first 3 days, and a medical sickness certificate from a physician is necessary from the fourth day. The employer covers sickness compensation for the first 16 days, while the National Insurance Administration covers from the 17th day up to a maximum of 52 weeks. The national sickness benefit register contains information on all sickness absence paid by the National Insurance. In 2003, it included all certified sickness absence lasting >16 calendar days and <1 year. In this study, sickness absence episodes >16 days, and terminated 1 January–30 June 1996 and 1 January–30 June 2003, were analysed by diagnostic code. Civil servants were not included in the register in 1996, and hence were also excluded from the 2003 data. Actively job-seeking, unemployed persons have a right to sickness benefits, and are included in the register.

The denominator used was the number of persons in the Norwegian workforce in 1996 and 2003, as registered by Statistics Norway (http://statbank.ssb.no/statistikkbanken/). This also included unemployed persons. Civil servants were excluded.

Sickness absence episodes are supplied with a diagnostic code, as given by the doctor on the sickness absence certificate. Coding is done according to ICPC classification system [22].

The single items of the SHC questionnaire were matched with the corresponding International Classification of Primary Care (ICPC) diagnostic codes (Table 1, available as Supplementary data at Occupational Medicine Online), including all ICPC codes that could lead to complaints for that single item. The SHC questionnaire measures all complaints experienced during the last month, and does not ask for diagnosis, cause or severity. Therefore, we have included both ICPC symptom codes and disease codes in our study. The SHC items ‘upper back pain’ and ‘low back pain’ were pooled to a single item of ‘back pain’ to correspond with the back-related ICPC codes. For the SHC items ‘heat flushes’ and ‘stomach discomfort’, no corresponding ICPC codes were found.

SPSS 12.0 for Windows was used for the statistical analyses. Differences in gender, educational level and age were tested with chi-square tests and independent sample t-test. Before the analyses, the data were categorized in two different ways in terms of complaint status: (i) no complaints (score 0) or complaints (score 1, 2 or 3) and (ii) no/little complaints (score 0 or 1) or substantial complaints (score 2 or 3). Prevalence of the SHC single items and the five dimensions were calculated for both years, and differences were tested with chi-square tests. Percentage changes in prevalence of complaints (both any and substantial complaints) and prevalence of sickness absence were also calculated.


   Results
Top
 Abstract
 Introduction
 Methods
 Results
Discussion
 Conflicts of interest
 References
 
There were no gender differences between the samples in 1996 (49% women) and 2003 (47% women). There were statistically significant differences between the two samples in educational level and mean age. In 1996, 15% reported 0–9 years of education, 41% reported 10–12 years and 44% reported >12 years, whereas in 2003 the distribution was 10%, 40% and 50%, respectively (P = 0.012). Mean age was 40 (95% CI: 39–40) years in 1996 and 43 (95% CI: 42–43) years in 2003 (P < 0.001).

The prevalence of musculoskeletal complaints did not show any major change from 1996 to 2003 (Table 2). There was a small reduction for the total musculoskeletal factor from 81% to 75%, mainly due to the large reduction of the prevalence of headache. There was a significant decrease of substantial headache, neck and shoulder complaints (Table 2).


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  		Table 2 Percent of individuals reporting any (score above 0) and substantial (score above 1) SHC in 1996 and 2003. Differences tested with chi-square tests

 
There was no change in the prevalence of pseudoneurological complaints, except for a significant decrease in the prevalence of palpitation, dizziness and depressive emotions (Table 2). There were significantly fewer individuals reporting substantial palpitation, tiredness and depressive emotions in 2003 than in 1996.

The prevalence of the total gastrointestinal score decreased significantly from 58% to 47% from 1996 to 2003 (Table 2); however, only bloating, diarrhoea and constipation changed significantly. There was a significant decrease of substantial stomach discomfort and pain, bloating and diarrhoea.

The total allergy score did not change from 1996 to 2003 (Table 2). However, there was a significant decrease in chest pain and an increase in the prevalence of allergy and substantial asthma.

Significantly fewer reported flu and flu-like complaints in 2003 than in 1996.

We found that the total prevalence of sickness absence (all causes) increased from 1996 to 2003. There were 174 564 cases (9% of working population) of sickness absence in the first 6 months of 1996, and 238 311 cases (12% of working population) in the first 6 months of 2003. The diagnoses corresponding to the items in the SHC questionnaire accounted for 51% of all sickness absence in 1996 and 53% in 2003. In 1996, diagnostic codes corresponding to musculoskeletal complaints accounted for 34%, pseudoneurological complaints 12%, gastrointestinal complaints 2%, allergic complaints 3% and flu-like complaints 2% of sickness absence. In 2003, musculoskeletal complaints accounted for 30%, pseudoneurological complaints 18%, gastrointestinal complaints 2%, allergic complaints 2% and flu-like complaints 1% [see Table 1 (available as Supplementary data) for number of cases for all diagnoses].

There was poor concordance between percentage changes in the five dimensions of health complaints and changes in corresponding sickness absence (Figure 1). There was an increase in sickness absence for all single complaints measured in this study, except chest pain, ulcer and non-ulcer dyspepsia and cold/flu. The main pattern for the prevalence of complaints during the 7 years was no major change or a small decrease.


Figure 1
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  		Figure 1 Change (%) between 1996 and 2003 in prevalence of the five SHC dimensions and prevalence of sickness absence for corresponding ICPC diagnoses.

 
Both any and substantial headache decreased by ~30%, whereas attributable sickness absence increased by >80% (Figure 2). The prevalence of back pain and the prevalence of back pain-related sickness absence were stable during the 7 years. The largest increase in sickness absence was found for pseudoneurological complaints, with a 100% increase (Figure 1); however, the corresponding change in prevalence of complaints was a decrease of 3%. Tiredness was the single complaint with the largest change in sickness absence, with an increase of >350% from 1996 to 2003 (Figure 2). The corresponding change in prevalence of complaints was an increase of 2% for any complaints and a decrease of 41% for substantial complaints. Palpitation, sleep problems, dizziness, anxiety and depression showed from 50% to 180% increase in sickness absence, whereas the change in prevalence for these complaints ranged from a decrease of 60% to no change at all.


Figure 2
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  		Figure 2 Change (%) between 1996 and 2003 in prevalence of single items of SHC and prevalence of sickness absence for corresponding ICPC diagnoses. Change (%) in prevalence of any complaints (score above 0) and change in prevalence of substantial complaints (score above 1) are shown. *No corresponding ICPC diagnosis.

 
Sickness absence for gastrointestinal complaints increased by 30%. The prevalence of gastrointestinal complaints, however, decreased with 19%.

The total allergy factor showed a 12% decrease in prevalence of complaints and a 5% increase in the prevalence of sickness absence. Substantial asthma increased by 200%; however, there was a small decrease in sickness absence of 7%.


   Discussion
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
Conflicts of interest
 References
 
The prevalence of health complaints in Norway as measured by the SHC questionnaire was high and relatively stable from 1996 to 2003. Sickness absence for health complaints by the corresponding ICPC codes, however, showed a general increase.

The SHC questionnaire was designed to measure common and prevalent health complaints in the general population. It has been used in several studies [6,9,15,18]. The corresponding diagnostic codes, used in the sickness absence register, were used in over half of all sickness absence cases, thus demonstrating the importance of these complaints in relation to working life.

The prevalence data on health complaints are based on data from a professional opinion poll, and different interview methods were used in 1996 and 2003. It has been reported that mailed questionnaires are associated with underreporting of medical conditions, compared to telephone interviews [23]. Other studies have shown these methods to give comparable results on self-reported health [24,25]. However, the change of methods could influence the report rate of some somatic and mental health complaints differently. It has been shown that people tend to minimize or avoid reporting psychological problems when interviewed face-to-face as compared to anonymous questionnaires [26], and the same could be true for telephone interviews. This could partly explain why we found a decrease in mental health problems and some of the gastrointestinal complaints that people might find unpleasant or embarrassing to report. It is unlikely, however, that the change of methods could explain the general picture of stability found in this study. The study sample in 2003 was slightly older and better educated than the 1996 sample. Age is known to show a positive relationship with prevalence of some health complaints and a negative relationship with others, whereas higher education is known to be associated with lower prevalence of health complaints [6], so the actual prevalence could be somewhat different. However, again it is unlikely that the small but significant differences could explain the general picture of stability found in this study.

The national sickness benefit register is an accounting system for the payment of benefits, and is revised, audited and quality controlled. The diagnosis on sickness certificates might be incorrectly written and coded, and we have no way of checking possible misclassification. According to previous studies, such misclassification occurs only to a limited extent [17]. Our study can only show relative changes in sickness absence in the Norwegian population, as we do not have information on prevalence of complaints and sickness absence from the same individuals.

The stability of prevalence of complaints is supported by national statistics from the surveys of living conditions in Norway. These statistics show that from 1998 to 2002, the percentage of the total population that reports chronic or recurrent complaints like bodily pains, headache, tiredness and sleeping problems has not changed [27]. The increase in asthmatic complaints is in accordance with another Norwegian study that reported an increase in self-reported asthma in the population during the last decade [28].

The diagnoses that showed the largest percentage increase in sickness absence were sleep problems, tiredness, anxiety and palpitation, although the absolute number of individuals with sickness absence for these complaints was small. This is in agreement with earlier reports. The distribution of diagnoses on sickness certificates has for a large part been unchanged from 1994 to 1999, with the notable exception of a relative increase in psychological diagnoses [29].

The main finding in this study is poor concordance between the change in prevalence of health complaints and the change in the prevalence of sickness absence for diagnoses corresponding to these complaints. The increase in sickness absence cannot be explained by a corresponding change in health complaints. A recent study from Sweden has shown that the correlation between illness, disease and sickness absence is low and unstable over time [30].

There was no major change in the Norwegian sickness compensation during the study period, which could explain the increasing sickness absence. One other factor known to influence sickness absence is unemployment [31]. In periods of rising unemployment, sickness absence rates tend to fall. In the period from 1996, unemployment fell from 4.5% to a low of 3.4% in 2000, but then rose to return to 4.5% in 2003 [32]. It is, therefore, not possible to explain the rising sickness absence rates in this period by rising employment rates.

Another explanation for the increasing sickness absence could be changing demands and an increase in reorganizations in working life. Norwegian employees report an increase in demands, conflicts and insecurity in their job situation [33]. Several studies have shown a relationship between demands, health and sickness absence [34,35]. However, although increased demands and insecurity might lead to more sickness absence, it should also lead to more complaints and we did not find any such general increase.

Pain is by definition subjective and the consequences of pain regardless of the causal relationship will be influenced by many factors, including the individual's perceptions and expectations. The lack of accordance between changes in sickness absence and prevalence of complaints could be due to changes in the interpretation, acceptance and attitude towards SHC. Are these complaints symptoms of a disease—or normal inconveniences? Increasing health worries could contribute to increased utilization of the health service and sickness compensation system.

This study shows that health complaints are very frequent, with no major, or a somewhat decreasing prevalence from 1996 to 2003. The increased prevalence of sickness absence due to such complaints in the same period is most likely to be explained by multifactorial causes. The results show that the association between health complaints and sickness absence is not straightforward. More studies are needed to investigate the relationships between these factors, prevalence of complaints and sickness absence.


Key points
  • The increased sickness absence in Norway from 1996 to 2003 cannot be explained by an increase in health complaints in the general population in the same period.
  • The increase in sickness absence is most likely to be explained by multifactorial causes, such as changes in working life and health expectations.
  • More studies are needed to investigate the relationships between these factors, prevalence of complaints and sickness absence.

 


   Conflicts of interest
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Conflicts of interest
References
 
None declared.


   Acknowledgements
 
The project was funded by the Norwegian Ministry of Health and Social Affairs and the Norwegian Research Council. We thank Rolf Svendsrød at Norwegian Gallup and Anne Sagsveen at the National Insurance Administration for good collaboration. Holger Ursin provided valuable comments to the manuscript.


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