Opium is one of many drugs that decrease pain [1]. Little is know about whether chronic pain leads to opioid misuse; studies have shown that from 3% to 23% of patients with chronic pain are addicted to opioids [2,3]. Some believe chronic pain leads to opioid use, more hospitalization, reduced physical efficiency and more psychiatric symptoms [4]. Others argue that it is the biopsychosocial nature of humans, rather than the pain itself, that predisposes certain individuals to opioid use [5].

Between 9% and 27% of white male opioid addicts reported that their addiction started with a prescription from a doctor for an opioid analgesic to treat a painful condition [2,3]. In a similar recent study of 58 patients, the authors warn physicians that severe oral opioid dependency occurs more frequently than previously recognized [6]. In a national study of opium addicts in the Islamic Republic of Iran, pain was mentioned by 17.5% as a trigger to opioid use [7].

There are multiple factors that have been documented as associated with opioid use, including demographic characteristics, personality, genetics and environment. Some of these include: younger age, being divorced/widowed/separated, having a family member who uses drugs, encouragement to use by friends or others [8–10], failure in education, severe economic deprivation, social isolation (separation from family) [10], illiterate or poorly literate father or mother [9,11], unemployment [11,12], cheap price of opioids [13], not knowing the harmful effects of opioids or believing they are useful [9,10,12], cigarette smoking [8], alcohol use [11,14,15], history of drug use [16], psychosocial problems such as depression [9,10,17,18], HIV positive, history of sexual abuse [19], past history of consultation in opioid clinic and/or treatment during 12 months before being in prison [20].

As far as we know, there has been no evaluation of the prevalence of opioid use in patients suffering from pain in the Islamic Republic of Iran. Our study was done in the south-east of the Islamic Republic of Iran, an area which is the main gateway of opium transit from Afghanistan and Pakistan to Europe and where opioids may be easily accessible. Sistan va Baluchestan province is also socioeconomically a very deprived province. We studied opioid use in patients with pain attending clinics in Zahedan, the main city of the province. The aims of the study were to ascertain: whether chronic pain causes opioid use; the prevalence of opioid use in patients presenting with pain; and the predisposing factors for opioid misuse (i.e. why one patient consumes opioids and another does not).

A cross-sectional study was conducted on 480 consecutive patients who presented with pain at the study clinics in Zahedan. There is no pain clinic in Zahedan, so patients with pain are referred to various clinics within the city. The 10 clinics selected were those where specialists agreed to participate in the study: 3 neurosurgery, 3 psychiatry, 1 preoperative anaesthesia, 1 physiotherapy, 1 emergency and 1 neurology clinic. Around one-third of consecutive patients attended the neurosurgery clinic, one-third the psychiatry clinic and one-third the other clinics. The study was conducted over 2 months in March and April 2001. The inclusion criteria were all patients aged over 16 years old with a chief complaint of pain.

A questionnaire was devised to collect data on sociodemographic variables, characteristics of pain and opioid use (types of opioids taken, amounts taken and routes of administration). In our study, chronic pain was defined as frequent or constant pain for a duration of 6 months or more. Acute pain was defined as pain frequently (always/often) for 1 month or less. Opioid use was defined as occasional or regular use of opium, opium residue (shireh), heroin, morphine or codeine in the previous year. The questions covered 18 factors that have been associated with opioid use: age, male sex, unemployment, illiteracy, urban residency, divorce, death of spouse, location of pain, duration of pain, frequency of pain, opioid use recommended by friends or physician, cigarette smoking, alcohol drinking, history of opioid use in family, history of opioid use in friends, decreased economic situation, death of friend or family member and poor psychological health. Our practical definition of poor psychological health was the patient’s report of opioid use for relief of psychological stress, history of consultation for a psychological problem or history of psychological treatment. The questionnaire was prepared at the pain clinic of the Medical University of Iran following a literature review and was modified in Zahedan University of Medical Sciences. Four other psychiatrists reviewed the questionnaire for face and content validity.

The specialists at the clinics delivered the questionnaire to patients by interview to minimize bias between literate or illiterate patients. The specialist and assistant in each clinic were trained in how to deliver the questionnaire.

Comparisons of patients with and without opioid use and associated factors were made with chi-squared, Student t-test and logistic regression analysis. SPSS, version 6 was used for the statistical calculations.

Of the 480 patients with pain, 57.5% were female. The mean age of pain patients was 36.0 ± SD 13.9 years. A total of 81.0% were married and 6.0% had experienced the death of a spouse. Only 7.0% of patients were unemployed; 77.0% of female pain patients were housekeepers. There were 46.7% illiterate patients (62.0% of the women and 25.1% of the men) and 32.1% had attended only guidance school.

The overall prevalence of opioid use was 28.5% (137/480) in patients presenting with pain. Opium and opium residue (shireh) was used by 65.9% and 15.9% of users respectively. Most users (92.7%) had consumed for more than 2 months duration. Consumption was 1 or more times per day for 70.1% of users. The most common method of consumption was inhalation, used in 59.1% of cases. There were 5 patients using cannabis (hashish).

Opioid users claimed pain as an origin of their opioid use in 79.6% of cases. Although opioid use was more prevalent in chronic pain than acute pain (26.3% versus 15.9%), the result was not statistically significant (P > 0.05). On the other hand, statistical analysis did not show that pain preceded opioid use (P = 0.074).

In the first stage of analysis, 11 of the 18 factors included were associated with opioid use: age, sex, occupation, education, death of spouse, consultation for a psychological problem, cigarette smoking, alcohol, opioid use in the family, opioid use in friends, and worsened economic situation. The number of alcohol drinkers was low.

Opioid use was 28.5% among patients presenting with pain to clinics in this city in the Islamic Republic of Iran. Availability of drugs is a potent predisposing factor to opioid use [21]. The nearby countries of Afghanistan and Pakistan are 2 of the major production areas in the world, named the ‘golden crescent’. When opioids are more readily available, the stigma in society is reduced and if they are cheap, the vicious cycle of dependency and crime is less [2].

In a previous study, 81% of codeine-dependent patients said that their codeine use started with a chronic pain problem [14]. In our study, a similar proportion of opioid users (79.7%) told us the same. However, we found no statistically significant relationship between the presence of chronic pain and opioid use in pain patients.

The identification of an addictive disorder in a patient with chronic pain does not necessarily preclude the use of opioids as a component of pain management, unless maladaptive patterns of behaviour develop which define addiction. These are adverse consequences such as persistent over- sedation, loss of control over use and preoccupation with using opioids despite adequate analgesia [26]. Diagnosing addiction and drug-seeking behaviour is important in chronic pain patients [27].

It should be emphasized that pain is not the main culprit in opioid misuse; biopsychosocial risk factors are especially important for addiction disorder. The Screening Instrument for Substance Abuse Potential (SISAP) [28] helps the clinician categorize patients into lower or higher risk of abusing prescribed opioids. Patients who are at higher risk for substance abuse include those whose exceed 3–4 alcoholic drinks per day, those who admit to marijuana or cannabis use in the past year and patients under 40 years old who smoke cigarettes [15].

We found 5 risk factors associated with opioid use in pain patients: previous opioid use by friends, occupation, cigarette smoking, neuropsychiatric consultation and death of a spouse. A cross-sectional non-concurrent cohort study among young males in south-west China using multivariate analysis identified the following significant risk factors for drug use: being divorced/widowed/separated, having been encouraged by friends/others to try drugs, smoking cigarettes, and having a family member who used drugs [8]. In our study, smoking cigarettes and/or being widowed were also significantly associated with opioid use, but being divorced/separated, having been encouraged by friends/others to try drugs, and having a family member who used drugs were not significantly associated with opioid use. In a European multicentre study of drug injecting in prison, friends injecting opioid substances were identified as a risk factor [20]. The role of friends was the most important associated factor in our study. It seems friends have more influence than families in this particular situation.

There was a higher level of consultation for a psychological problem among opioid users than non-users in our study. Another study has shown a 23% depression rate and 21% anxiety disorder rate among codeine-dependent patients [14].

Predisposing factors for illicit drug use have been shown to be unemployment and poor education [12]. In our study, however, people working in business were the most likely to use opioids. Greater spending power for luxury goods and increased leisure time over recent decades have been linked to increased drug abuse in society [21].

In an analysis comparing addicts and non-addicts in the Islamic Republic of Iran, cigarette smoking and alcohol were associated with opioid use [11]. Opium is the most commonly misused substance in our country [7,11]. These agree with our study showing an association between cigarette smoking and opioid use particularly opium.

In other studies [7,11], there were more men than women using opioids, but in our study sex was excluded by the logistic regression analysis. Historical anecdotes suggest that more addicts were women 200 years ago [29], but it seems that nowadays men have more opportunities to misuse opioids [30].

There is a high prevalence of opioid use in patients who complain of pain in Zahedan. Opioid use in friends was the most important associated factor for opioid use in pain and further research into this would help parents, teachers, trainers and leaders of society to know how to deal with this. Clinicians with pain patients should be aware of the other factors associated with opioid use, such as cigarette smoking and asking for psychiatric support from neuroconsultants. More support for widows and widowers, who are a small but vulnerable group, may be needed. Pain provides a guilt-free reason for opioid use and more research is needed into opioid use in society generally, not just small groups such as students, and the biopsychosocial factors involved.

This work was supported in part by a grant-in-aid for scientific research from the Zahedan University of Medical Sciences. We thank our partners in the pain clinic of Medical University of Iran for taking part in preparing the research proposal, and in UPMC and Zahedan University of Medical Sciences for technical support and preparing and editing the manuscript. The following investigators collaborated in the study: Drs Seyyed Alireza Sadjadi, Mohammed Safdari, Mehran Sedagat-kish, Bahram Keshmirian, Seyyed Mostafa Alavi, Noutizehi-Shahbakhsh, Ali Moghtaderi, Tahereh Zohravi, Eemani Vahhashi, and Mr Abbas Arab.

30. Van Etten ML, Neumark YD, Anthony JC. Male–female differences in the earliest stages of drug involvement. Addiction, 1999, 94(9):1413–9.