Background
Neck pain is a common health problem [
1] and mostly characterized by recurrent episodic or persistent fluctuating pain rather than a single isolated episode [
2‐
5]. Studies indicate that these pain patterns are associated with increased disability and reduced quality of life compared to having a single pain episode [
2,
5,
6]. Thus, neck pain is also a substantial socioeconomic burden [
7,
8].
To date, the prognosis of neck pain is poorly understood, and no cure exists. For patients that experience recurrent and persistent neck pain that negatively affects daily living, pain management may be the most effective approach to reduce the number and impact of relapses and maintain good function and quality of life. In chiropractic practice, patients with these pain patterns may be recommended maintenance care (MC) [
9,
10]. MC is a traditional chiropractic approach described as continued care after optimal benefit is achieved in an initial care plan [
11‐
14]. Such an initial care plan typically lasts between 2 and 4 weeks [
15,
16]. The purpose of MC is to reduce the risk of relapse and maintain good daily function [
11‐
14], the frequency is typically treatments every 3 months, and the treatment entails manual therapy and advice on lifestyle and exercise [
13,
17]. Receiving MC (i.e. continued care as decided by the chiropractor) compared to receiving symptom-guided therapy (i.e. further care decided by the patient when they perceive a need) have been examined in patients with recurrent and persistent low back pain [
18]. It was concluded that MC was more effective in reducing the total number of days with bothersome pain over a year’s time [
18]. However, MC is currently being investigated and not included in clinical practice guidelines as a recommended evidence-based treatment strategy for prevention.
Focus groups and surveys have systematically explored chiropractors’ indications for using MC in patients with low back pain [
13]. According to these studies, MC is offered to patients who have experienced
previous pain episodes,
long pain duration, and have shown
improvement after initial treatment [
19‐
21]. These indicators for MC were confirmed in an observational study of patients with low back pain and
previous pain episodes was found to be a strong predictor for recommending MC [
22]. In addition, the recommendation of MC may also depend on the chiropractor and the clinical setting. Chiropractors who were trained in the US compared to Europe, as well as chiropractors with more experience and clinic ownership, tend to recommend MC more frequently and to a greater extent to their patients [
19].
Most studies on clinical indications and efficacy of MC have been performed in patients with low back pain [
13]. One study explored the effectiveness of preventive spinal manipulative care with and without a home exercise program, in comparison to no treatment in patients with neck pain [
23]. However, the study did not use the clinical indicators as criteria for receiving MC. Musculoskeletal pain, including low back and neck pain, share many common features on clinical course, prognostic factors, and prognosis [
2,
24‐
29]. Hence, there are reasons to believe that patients with neck pain are managed similarly to patients with low back pain [
30,
31], and this study aimed to investigate if the clinical indicators found for patients with low back pain apply to patients with neck pain in chiropractic practice. We used data from a cohort study of patients with neck pain. After four weeks following inclusion, chiropractors assessed if further treatment was recommended or not [
15,
16]. This recommendation was used as a proxy for MC.
Specifically, the objectives were (1) to investigate whether the clinical indicators identified for low back pain were associated with being recommended continued care for patients with neck pain, (2) whether this recommendation was dependent on chiropractor characteristics, and (3) to examine if the number of identified clinical indicators influenced this recommendation.
Discussion
This study examined if previously identified clinical indicators (previous pain episodes, a long pain duration and improvement after initial treatment) for recommending MC to patients with low back pain also applied to patients with neck pain who were recommended continued care beyond 4 weeks. Having a long duration of current neck pain was found to be the only clinical indicator to predict if continued care was recommended to the patient by the chiropractor. However, a recommendation for continued care was not associated with chiropractor characteristics. We found that when all three clinical indicators were present, 39% of patients were recommended to receive continued care. As the number of indicators decreased, the likelihood of the recommendation decreased as well, suggesting the relationship between indicator count and the recommendation for continued care.
Our findings indicate that clinical indicators for recommending continued care to patients with neck pain are different from those used for recommending MC to patients with low back pain. A study investigating the rationale for MC in a low back pain population found that patients perceive MC to prevent recurrences and help them remain as pain free as possible [
17]. This matches the beliefs of chiropractors where low back pain episode frequency and duration (both over the past year and of the present episode) were considered important factors influencing the recommendation of MC [
12,
19]. In a study of patients with low back pain, previous episodes were found to be the best predictor of MC recommendation [
22]. The same study found that patients reporting a long duration of their low back pain were not statistically associated with such a recommendation.
A long duration of pain and previous pain episodes are likely to be highly correlated, and a history of long pain duration has been associated with an unfavorable outcome [
48]. Thus, it seems appropriate that the severity and persistence of a complaint are related to an approach that involves recommending continued care. Moreover, most predictors of unfavorable outcome are similar for low back and neck pain [
26,
28]. Due to similarities between neck and low back pain, the discrepancy between our results and previous findings for low back pain may be a random finding. Nevertheless, this study needs to be replicated in a new cohort to confirm the results.
Interestingly, reporting improvement with initial treatment by the fourth week was not found to influence continued care. Thus, despite that improvement with initial treatment has been suggested as an important indication for MC by chiropractors in the Nordic countries [
22], it was not found to be an indicator for continued care in our study. There seems to be a variety of aspects associated with the use of MC and the evidence is conflicting regarding whether improvement with initial treatment (i.e., the patient reports benefit from initial treatment) is a necessary indicator [
11,
14,
22].
The accuracy of the multivariable regression models was examined using the AUC. Overall, the information provided by the indicators allowed continued care to be distinguished from not continued care with a moderate degree of accuracy (AUC = 0.76). Thus, many patients with all three indicators were frequently regarded as not being candidate for continued care. When adding chiropractor characteristics in the model, the AUC increased to 0.80. Even acknowledging that chiropractor characteristics might impact the improved AUC outcome, no statistically significant association between chiropractors and the outcome was found. Moreover, it is important to note that the confidence intervals for the AUC values overlapped suggesting the observed increase from an initial AUC of 0.76 to 0.80 may not be statistically significant. Therefore, the practical significance of this improvement remains uncertain.
One study found that the initiation of MC is a shared decision between the patient and the chiropractor [
49]. At baseline, we observed some differences in characteristics of patients with continued care planned compared to patients with no continued care planned. Previous research indicate that the intent of MC is to prevent future pain episodes, and it is logical that patients with a long pain duration and previous episodes may be recommended continued care, based on their previous pain experience [
12,
17,
21]. In addition, clinicians may (perhaps even subconsciously) consider present bio-psycho-social factors to contribute to the development of persistent pain [
50‐
52] before recommending continued care. For instance, studies have found that patients with a less favorable psychological profile report better outcomes from a MC approach [
53,
54]. Current evidence suggest that clinicians assess patients’ psychological distress together with their previous pain history, initial treatment effectiveness and patient preferences when identifying patients with low back pain suitable for MC [
55].
Characteristics of a chiropractor (such as their gender, age, place of training, year of graduation, number of years in practice, and specialty) will be the same exposures for patients visiting a specific chiropractor, but different from those of another chiropractor. A Danish study found that place of training and number of years in practice were associated with the use of MC [
19]. However, we did not find any significant associations between chiropractor characteristics and outcome. In our study, most chiropractors had recruited three patients or less, therefore high, and low use of continued care could not be explored. Moreover, studies investigating evidence-based practice in chiropractors found that traditional knowledge and expert opinions were used to the same extent as clinical guidelines when managing patients [
56‐
58]. We hypothesize that these aspects may well (consciously or subconsciously) affect what patients are recommended continued care, which may have had an impact on the results of this study.
Strengths and limitations
The study was a multicenter study gathering data on patients with neck pain from many Norwegian chiropractors, thus likely to reflect clinical practice and result in good external validity. We consider our sample to be representative when compared to previously published work [
59]. Our study population includes patients with neck pain commonly seen in primary care. The baseline characteristics and outcomes reported by our chiropractic patient population align with other cohort studies from primary and general care populations [
2,
3,
60], indicating that our sample can be generalized to other neck pain populations.
We used digital questionnaires that required all questions to be answered, eliminating the issue of missing data. Our study had a limitation regarding loss to follow-up, as 4% of the included patients lacked information from chiropractors regarding continued care at the 4-week follow-up. This may raise a question about possible attrition bias. To address this, we tried to contact all chiropractors (by phone and/or mail) and ask about reasons for not completing the questionnaire. The primary reason reported was lack of time. There were no obvious differences observed between chiropractors caring for patients with or without information in the analyzed sample. Additionally, the excluded patients without information showed only minimal variations from the analyzed sample, indicating a limited risk for attrition bias to impact the study findings.
We tested the associations in both univariate and multivariable models. The sample size (n=164) was considered sufficient to explore the predictive performance and strength of association between three indicators, chiropractor characteristics and outcome [
47]. A potential limitation to consider is the lack of statistical testing and consideration of potential confounding factors, which could have influenced the observed relationship between indicator count and the recommendation for continued care.
Another potential limitation is that the chiropractors in the study were not specifically asked whether they considered the individual patient as candidate for MC or if they recommended a preventive approach. The analysis is based on their recommendation of continued treatment. Our results are therefore not directly comparable with those of MC studies. Neck pain is a heterogeneous condition with distinct clinical features and various responses to treatment, so the intent of continued care may have been diverse and not solely preventive. For instance, patients being slow responders to initial care plans may have required extended treatment plans, and as a result, been deemed suitable for continued care. Therefore, patients may have been recommended continued care with different objectives and, not solely preventive. However, we do believe that a recommendation for continued care may serve as a proxy for a MC recommendation.
One may argue that a follow-up period of four weeks is too short to consider a continued care approach for patients with low back or neck pain. We found that patients recommended for continued care were more severely affected at baseline and at 4-week follow-up. These patients reported higher pain intensity, a longer pain duration, and a higher number of MSK pain-sites compared to patients not being recommended continued care. One may hypothesize that the chiropractors were sensitive to these hallmarks and identified these patients as a subgroup with a more severe pain affliction. Thus, continued care would be a reasonable option to manage their condition.
Clinical implications
In patients with neck pain, a long duration of pain was a strong clinical indicator for the chiropractor to recommend continued care. Thus, the duration of neck pain may have important clinical implications.
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