The high overall CAM use (87%) despite substantial differences in disease-specific aspects of the two patient populations revealed in the study is in line with population-based findings showing frequent CAM use in LBP (57%), cold (29%), headaches (19%), strain (15%) and gastrointestinal ailments (12%) .
LBP and headache patients differ regarding demographic data (Table 1), reflecting the characteristics of the diseases (e.g. higher age and later onset in LBP), which also can influence lifetime experience with CAM. The educational level differs significantly with a higher portion holding a university degree among headache patients. This may have two reasons: 1. LBP patients are older and education levels increased during the last decades 2. Patients with lower education are likely to do manual work and therefore suffer more from LBP. Duration of disease is significantly longer for headache patients due to the onset of primary headache in adolescence, whereas LBP mostly begins in middle-aged or older people.
Patients with LBP were more likely unable to work than headache patients. Headache patients suffer most from episodic headache with only half the pain days per month compared to LBP. Therefore, the intake of analgesics in LBP is more than twice as high as for headache patients. However, there were no differences in mean pain intensity in the two groups. The significantly higher number of affected family members in headache compared to LBP (Table 1) reflects the genetic background of primary headaches.
Chronic pain was found to double the odds of using CAM . A recent Canadian survey found migraine and asthma as predictors for higher CAM use in the population. However, this was not supported for other chronic diseases with a rather constant nature of symptoms (significantly lower CAM use in diabetes, no significant rate of CAM use compared to general population in epilepsy) .
Conventional treatment often does not result in resolution of symptoms; therefore patients look for alternative treatment options. In 2002, a population-based US survey revealed that 6% of the population use CAM for treatment of LBP . In our study, acupuncture, massages, and thermotherapy are the most frequent CAM therapies in headache and in reverse order for LBP. The most frequently used CAM therapies in Germany are exercise therapy, herbal medicine, hydrotherapy, medical massage, homeopathic remedies and acupuncture . Considering the different therapeutic impact of physiotherapy in headache and LBP, physiotherapy was not defined as a CAM modality. Some specific techniques are recommended in treatment guidelines especially for LBP. However, the evidence for physiotherapy and endurance sports is weak in headache treatment while more evidence is found in LBP [6, 26, 27]. There is no evidence supporting the use of transcutaneous electrical nerve stimulation (TENS) in headache or LBP therapy [5, 28].
Understanding the high frequency of CAM use leads to an analysis of motivations and barriers to treatment. Prior CAM use was associated with current CAM use, showing the adherence to previous experience and behavior. 'Lack of effectiveness of conventional treatment' was given as the strongest motivational reason for CAM treatment. This is not surprising regarding clinical trials in headache prophylaxis showing a 50% reduction of headache days in only half of the patients. Similarly discouraging data are reported for treatment of LBP. Effects of acute pain medication as well as of prophylactic medication were estimated only as "moderate" in a recent review . Contradicting this, dissatisfaction with conventional treatment was not significantly associated with more frequent CAM use in our study. However, patients expect an improvement in the chronic condition. CAM therapies are estimated as helpful by most patients and they would like to have more information on CAM and would appreciate prescriptions of CAM . Headache patients raised three times more concerns about permanent conventional drug intake than LBP patients. This could be a consequence of the longer duration of disease and repeated frustration about past treatments. Notably, concerns about drugs are four times more frequent in both groups than concerns resulting from bad experience with conventional medical practitioners.
In addition to the motivational factors, barriers for CAM use could be asked among the patients who had no experience with CAM. In the present study, the substantial number of patients offering no declaration of the given reasons in the questionnaire is striking (21.5% in headache; 82.4% in LBP), implying that possible reasons for not having used CAM are not sufficiently shown in the predetermined answer alternatives.
Apprehension of side effects is more important for headache than for LBP patients, but is a substantially itemized pro for CAM in both. This reflects the general assumption of many patients that CAM has no or fewer side effects. However, numerous herbal remedies have a potentially sensitizing capacity for allergic contact dermatitis and lead to IgE-mediated clinical symptoms or may have carcinogenic properties. Interaction between conventional drug treatment and CAM has to be considered. Injuries resulting in pneumothorax, cardiac tamponade or spinal injury and infectious complications are rare side effect of acupuncture .
To be active against the pain condition is reported as a motivation for CAM therapy more frequently in headache than in LBP patients. Furthermore, the wish to "leave nothing undone" was displayed clearly in both groups. The patients' activities in this point may reflect the pain intensity and frequency, the high burden of disease and unsatisfactory treatment experiences. However, no significant difference was found between CAM and non-CAM users regarding satisfaction with conventional pain treatment. This contradicts studies revealing an association between treatment satisfaction and search for CAM .
An important point is the advice of other persons to use CAM, which increases CAM use in both LBP (32.2%) and headache (40%) patients. This may correspond to family traditions or experience relayed from friends. Only a small group of patients gives other reasons for CAM treatment, reflecting the accuracy of the questionnaire to capture the relevant information. Other sources of information about CAM treatment are television, newspapers and internet. The gathering of more information from media coverage by the headache patients may reflect the lower mean age.
Cost and reimbursement from insurance may influence CAM use, too. However, only a small portion of the non-users among the headache (12.7%) and LBP (5.9%) patients give the cost as a barrier against CAM use. The situation of the statutory health insurance system in Germany should also be considered. For regular treatment, all costs are paid by the insurance directly without the need for prior administrative decision (including massages, homeopathic remedies and acupuncture in LBP but not in headache).
It might be helpful to ask patients about current CAM use to avoid side effects and pharmacological interactions. Their understanding of their treatment wishes and beliefs should also be taken into consideration. CAM therapies are popular especially among general practitioners in Germany; therefore it is not surprising that 71.7% of the headache and 77.4% of the LBP patients had talked about CAM use with their physicians.
As a limitation, the survey was performed among headache outpatients treated in tertiary centers and among inpatients with LBP. This population may be characterized through higher disability and burden of disease compared to patients of the general population. This could influence the frequency and motivation of CAM use. In future studies, we suggest using a more strict definition of CAM therapies and asking exactly the same questions in conditions to be compared. The specific healthcare system should be considered in comparing results from different countries. Reimbursement by the health care insurance might be important as an additional predictor of CAM use.