1. Background
Low back pain is one of the most common health problems in America and other countries of the world and is the most common cause of disability and absence from work (1-3). Lower back pain has many causes. Inter-vertebral disc herniationis one of the common causes of disease, especially in the third and fourth decades of life (4) and a major cause of function limitation and impairment of quality of life and chronic disability in both sexes (5). Prevalence of disc herniation is more common in men than women (6). Its prevalence is 7 - 37% indifferent countries and 8.20% in Iran, but there is no exact statistics regarding its prevalence rate in total (7). Inter-vertebral disc acts as a joint between the vertebrae and the shock-absorbing, in severe and sudden pressure on the spine, fibrous fibers of the outer layer of inter-vertebral disc would be torn and the central gelatinous disc substance would be herniated outward called inter-vertebral disc herniation (8). The destructive cause of lumbar disc is complex and not fully explained, so that its cause would be considered asa multifactorial disorder including a number of genetic and environmental factors and their inter actions (9). The most common clinical display of the disease is low back pain and the phenomenon is because of segmentalannulus innervation in lumbar disc, which is the most sensitive anatomically structure to pain (10, 11). Pain affects these patients’ health, performance and quality of life; chronic pains would cause physical and mental health involvement in adults and children (12). Daniel et al. stated that many patients with chronic pain have personality disorders, drug dependency, instability in family relationships and career incompatible (13). Many different treatment methods have been used to treat low back pain in patients with inter-vertebral disc herniation. Available treatments include proper training, physical activity without doing heavy work, medical treatments including non-steroidal anti-inflammatory drugs, physiotherapy, use of medical belts, acupuncture and herbal medicines (14, 15). The use of herbal medicines is apart of holistic medicine and its application along with modern medicine is effective in improving these patients (16). Infact, many complementary medicine majors such as acupuncture and herbal therapy are under the banner of natural medicine (17). In the recent years, herbal therapy has been more considered as one of the complementary medicine aspects (18). The use of medicinal plants in Egypt, Indian, China and Iran dates back more than other countries (19).
So far, many natural materials such as capsaicin have been used in traditional medicine to relieve low back pain. Capsaicin containssubstances like Capsanthin, henceexpected to have mutual effects of topical irritant (20). In a study, therapeutic effects of Capsanthin were shown in diabetic neuropathy, osteoarthritis and herpetic neuralgia (21). The use of these materials is because of such effects in combinations of these natural elements (20). Long-term and frequent use of capsaicin cream desensitizes secreting fibers of substance P and reduces the substance secretion, thus relieving pain (22, 23). This material has analgesic effect in cases such as muscular low back pains, pains arising from osteoarthritis, cluster headaches, lower urinary tract allergies and a variety of neuralgia (24). Weiser’s study showed that the ointment is helpful in the treatment of patients with chronic pain of soft tissue and is also effective in patients with chronic low back pain (25). The results of study conducted by Moghaddamnia showed that Capsaicin cream is only effective on pain at rest inosteoarthritis and has no effect on moving pain and arthritis; also it does not have any priority compared to Diclofenac gel and placebo ointment (26).
Despite the dramatic increase in clinical trial conducted in the past decade, only 2% of trials examined the issue of low back pain (27). Some studies have been performed on the effect of ointment made from the plant’s on peripheral pain including diabetic neuropathy, osteoarthritis, pain after surgery, chronic low back pain with unknown origin and soft tissue pain, butthere is no study about the use of complementary medicine methods including capsaicin cream in relieving pain in patients with low back pain caused by inter-vertebral disc herniation,in which pain originates from the central nervous system and stimulates recipients of pain in this area.
2. Objectives
No similar studies were found in Iran, so this investigation was performedto help improving the quality of care provided to patients and enhancing the quality of life and increasing their life satisfaction by decreasing patients’ pain. According to the World Health tendency to use complementary medicine, especially medicinal herbs, the use of capsaicin cream was assessed in relieving chronic low back pain because of inter-vertebral disc herniation to improve patients’quality of life.
3. Patients and Methods
This study was a random double-blind clinical trial with placebo-controlled performed on all patients with chronic low back pain caused by inter-vertebral disc herniation in Ahvaz. An approval was obtained from relevant authorities and patients. First, according to the research sample properties and inclusion and exclusion criteria, the number of research samples was determined as 40 patients. Based on pilot research and possibility of loss, 43 persons were randomly allocated into two groups. In the first group (n = 23), capsaicin cream and the second group (20 patients), ointments containing non-drug and ineffective material were used as non-drug control. Inclusion criteria were having low back pain for at least three months and chronic inter-vertebral disc herniation diagnosis of L5 and S1 by an expert, BMI less than 30, no pregnancy and lactation and not having skin diseases, obtaining a score higher than 5 based on the VAS criterion, no addiction and a history of surgery. Exclusion criteria were not willing to continue the intervention, mental illness and the need for surgery in the lumbar region.
Patients entered the study after diagnosis by a physician and completing a written consent form. The way of doing research, its terms and goals and the probability of being in one of the groups (treatment or placebo) were explained to all the participants. Drugs used in this study, capsaicin cream with 0.5% (Goldaru Co. Iran) and placebo ointment containing petrolatum and glycerin similar to pepper ointment for color, odor and concentrations but without effective substance, were prepared and coded by the research assistant in similar containers. Data collection instrument included demographic information and patient information and VAS questionnaire. VAS consists of 11 levels of pain intensity fromzero as no pain to 10 as the most feeling of pain. This questionnaire is a standardized scale to assess pain and its validity has been confirmed in several studies (28). In the first session, for both groups of patients, demographic information and patient information form completed by the researcher and using the patient records information in the office. Patients were trained about how to express pain intensity by VAS ruler and completed for each patient by the researcher.
Then the patients were instructed to put the ointment on painful position as a thin layer three times a day for three weeks. Patients were also explained that the drug may have adverse effects such as mild skin irritation, hot and itchy feeling and these adverse effects would be usually decreased or disappeared after frequent use, during the treatment period; patients were followed up by phone contacts. At the end of the first, second and third weeks post-treatment, the pain intensity was measured to evaluate treatment efficacy. And at the last session, the VAS questionnaire and the use of analgesics was recompleted for patients and satisfaction form was given to them to declare their satisfaction with the ointment. Finally the information obtained was analyzed using SPSS-18 software and descriptive statistics (frequency, percentage, mean, standard deviation) and inferential statistics (variance analysis, chi-square and paired t-test) (P < 0.005).
The ethics committee of Ahvaz Jundishapur University of Medical Sciences approved the study (ETH-303). Formal authorization was obtained from Disease Research Centre of Ahvaz Jundishapur University of Medical Sciences and Mahshahr oil hospital. Both the purpose and method of research were described for participants and informed consent to participate in the study was received from all of them.
4. Results
Two patients in capsaicin group were excluded from the study because of unwillingness and finally 43 patients completed the study. Participants’ information are presented in Table 1. Data analysis showed no statistically significant difference between the two groups for demographic properties.
Table 1. Distribution of Patients With Chronic Low Back Pain Due to Inter-Vertebral Disc Herniation Based on Demographic Specifications
| Placebo Group | Pepper Group | Demographic Profiles |
|---|---|---|
| Age, y | 44.1 ± 11.07 | 42.45 ± 11.07 |
| Gender | ||
| Male | 10 | 7 |
| Female | 13 | 13 |
| Marital status | ||
| Married | 18 | 17 |
| Single | 5 | 3 |
| Nationality | ||
| Arab | 10 | 9 |
| Persian | 8 | 5 |
| Other | 5 | 6 |
| Education | ||
| Illiterate | 10 | 6 |
| Lower diploma | 9 | 8 |
| Diploma and higher | 4 | 6 |
| Occupation | ||
| Housewife | 11 | 7 |
| Clerk | 5 | 5 |
| Hard jobs | 7 | 8 |
| BMI, kg/m2 | 25.55 ± 1.35 | 25.04 ± 1.37 |
Information about the patients’ disease is presented in Table 2. There was no statistically significant difference. Table 3 depictspatients’ information for their pain intensity mean at the beginning of intervention and the end of the first, second and third weeks of intervention. Pain intensity mean in the beginning of intervention in the two groups did not have a statistically significant difference (P = 0.793). Also the pain intensity means at the end of the first and second weeks of intervention between the two groups showed no statistically significant difference, respectively (P = 0.583) and (P = 0.73); however, there was a meaningful difference between the pain intensity mean at the end of third week of intervention and before the intervention by t-test (P = 0.008). Comparing the rate of analgesics use in beginning of intervention did not show a significant difference (P = 0.677), while comparing the rate of analgesics use after the interventions showed statistically significant difference (P = 0.007). Also examining patients’ satisfaction with the ointment use showed a significant difference between the two groups (P = 0.0001). Foradverse effects, three patients in the case group and one patient in the placebo group experienced mild redness and itching in the position they used the ointment.
Table 2. Average of Patients With chronic Low Back Pain Due to Intervertebral Disc Herniation Based on Duration and Kind of Drugs Used in Two Gropes
| Patient information | Pepper Group | Placebo Group | P Value |
|---|---|---|---|
| Disease duration, y | 7.7 ± 4.82 | 7.15 ± 5.01 | 0.72 |
| Type of analgesic | |||
| Ibuprofen | 11 | 12.60 | |
| Diclofenac | 7 | 5 | |
| Other medications | 5 | 3 | |
| Ointment side Satisfaction | |||
| Have | 3 | 1 | 0.292 |
| Not have | 20 | 19 | |
| Hospitalization history | |||
| Have | 8 | 6 | 0.5 |
| Not have | 15 | 14 | 0.50 |
Table 3.Average of Pain Intensity Based on the VAS Scale in the Two Groups of Pepper and Placebo before and after intervention
| Pain intensity | Pepper Group | Placebo Group | P Value |
|---|---|---|---|
| On arrival | 7.25 ± 1.25 | 7.35 ± 1.13 | 0.793 |
| First week | 7.05 ± 1.14 | 7.25 ± 1.11 | 0.580 |
| Second week | 6.65 ± 1.08 | 7.20 ± 0.96 | 0.073 |
| Third week | 5.95 ± 1.05 | 7.05 ± 1.39 | 0.008 |
5. Discussion
Low back pain is one of the most common complaints related to muscular-skeletal system.Many therapeutic approaches have been used to treat low back pain.
Despite access to conventional treatments, patients with chronic low back pains tend to use complementary and alternative medicine to relieve their symptoms (29). One of the treatment methods is use of complementary and alternative therapies such as medicinal herbs. The reason of using natural materials in relieving pain may be because these materials have fewer side effects due to the origin of preparation and less tissue damage than chemicals. In traditional medicine, the medicinal herbs were largely used among which the capsaicin has been widely applied (30).
In addition, to reduce systemic adverse effects of oral or parenteral drugs, the use of topical preparations has been more common in the treatment of chronic diseases such as chronic low back pain, which may require long-term treatment and the study aimed to apply capsaicin cream on 43 patients with chronic low back pain in the two groups of pepper [23] and placebo groups [20] treated three times a day for three weeks. The findings showed a statistically significant difference between pain intensity of patients in both groups at the beginning and end of the intervention (P = 0.0001). Chrubasik et al. showed that capsaicin cream generally improves pain in patients with chronic pain of soft tissue (25). Frerick et al. (31) showed that the use of capsaicin cream significantly reduced pain in patients with nonspecific chronic low back pain. Moghaddamnia et al. (26) showed that the use of capsaicin cream has not been effective for pain relief in patients moving with osteoarthritis and had nosuperiority over placebo ointment and Diclofenac gel in relieving pain at rest. This could be because of differences in the origin of pain and the disease stages. Comparison of pain intensity in the first, second and third weeks of intervention between the two groups showed that in the first and second weeks no relief effects were observed, and only at the end of intervention the ointment was more effective. While in Chrubasik study, during the first and second weeks of intervention, therapeutic effects of capsaicin cream were found (25), which is inconsistent with the present study and this could be because of differences in the origin of pain and disease type or a greater number of studied samples. Comparing the mean of using analgesics, there was a statistically significant difference in the two groups. In Kim et al. study performed on pain after inguinal hernia surgery in children, using the ointment reduced topical analgesics requirement to 31% (32), which is consistent with the present study. No statistically significant difference was observed between the two groups comparing unwanted adverse effects resulting from using the ointment such as itching, burning feeling and light red in the two studied groups after the intervention. In Frerick et al. study and Keitel study, adverse effects were seen in patients in the placebo and treatment groups, which is consistent with the results of this study (31, 33). Also comparing patients’ satisfaction of the two groups with performing the treatment group, they expressed their satisfaction using the ointment. In Chrunbasik et al. study, patients and researchers stated their satisfaction using the ointment and its safety (25),which is consistent with these results.
Use of capsaicin cream is a simple method without adverse effects for pain relief in patients with chronic low back pain caused by inter-vertebral disc herniation. However, it seems to achieve better results in case of longer duration of intervention.
5.1. Research Limitations
Pain is a subjective phenomenon and psychological, social and cultural factors affect it and controlling factors is out of the researcher’shands. Also responses given by the research units are considered correct and acceptable and there is no instrument to assess their verification.
