Few promising multivariable prognostic models exist for recovery of people with non-specific neck pain in musculoskeletal primary care: a systematic review

Development and internal validation of a multivariable prognostic model to predict chronic pain after a new episode of non-specific idiopathic, non-traumatic neck pain in physiotherapy primary care practice

OBJECTIVE

To develop and internally validate a prognostic model to predict chronic pain after a new episode of acute or subacute non-specific idiopathic, non-traumatic neck pain in patients presenting to physiotherapy primary care, emphasising modifiable biomedical, psychological and social factors.

DESIGN

A prospective cohort study with a 6-month follow-up between January 2020 and March 2023.

SETTING

30 physiotherapy primary care practices.

PARTICIPANTS

Patients with a new presentation of non-specific idiopathic, non-traumatic neck pain, with a duration lasting no longer than 12 weeks from onset.

BASELINE MEASURES

Candidate prognostic variables collected from participants included age and sex, neck pain symptoms, work-related factors, general factors, psychological and behavioural factors and the remaining factors: therapeutic relation and healthcare provider attitude.

OUTCOME MEASURES

Pain intensity at 6 weeks, 3 months and 6 months on a Numeric Pain Rating Scale (NPRS) after inclusion. An NPRS score of ≥3 at each time point was used to define chronic neck pain.

RESULTS

62 (10%) of the 603 participants developed chronic neck pain. The prognostic factors in the final model were sex, pain intensity, reported pain in different body regions, headache since and before the neck pain, posture during work, employment status, illness beliefs about pain identity and recovery, treatment beliefs, distress and self-efficacy. The model demonstrated an optimism-corrected area under the curve of 0.83 and a corrected R2 of 0.24. Calibration was deemed acceptable to good, as indicated by the calibration curve. The Hosmer-Lemeshow test yielded a p-value of 0.7167, indicating a good model fit.

CONCLUSION

This model has the potential to obtain a valid prognosis for developing chronic pain after a new episode of acute and subacute non-specific idiopathic, non-traumatic neck pain. It includes mostly potentially modifiable factors for physiotherapy practice. External validation of this model is recommended.

Improvements Are Needed in the Adherence to the TRIPOD Statement for Clinical Prediction Models for Patients With Spinal Pain or Osteoarthritis: A Metaresearch Study

This metaresearch study aimed to evaluate the completeness of reporting of prediction model studies in patients with spinal pain or osteoarthritis (OA) in terms of adherence to the transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD) statement. We searched for prognostic and diagnostic prediction models in patients with spinal pain or OA in MEDLINE, Embase, Web of Science, and CINAHL. Using a standardized assessment form, we assessed the adherence to the TRIPOD of the included studies. Two independent reviewers performed the study selection and data extraction phases. We included 66 studies. Approximately 35% of the studies declared to have used the TRIPOD. The median adherence to the TRIPOD was 59% overall (interquartile range (IQR): 21.8), with the items of the methods and results sections having the worst reporting. Studies on neck pain had better adherence to the TRIPOD than studies on back pain and OA (medians of 76.5%, 59%, and 53%, respectively). External validation studies had the highest total adherence (median: 79.5%, IQR: 12.8) of all the study types. The median overall adherence was 4 points higher in studies that declared TRIPOD use than those that did not. Finally, we did not observe any improvement in adherence over the years. The adherence to the TRIPOD of prediction models in the spinal and OA fields is low, with the methods and results sections being the most poorly reported. Future studies on prediction models in spinal pain and OA should follow the TRIPOD to improve their reporting completeness. PERSPECTIVE: This article provides data about adherence to the TRIPOD statement in 66 prediction model studies for spinal pain or OA. The adherence to the TRIPOD statement was found to be low (median adherence of 59%). This inadequate reporting may negatively impact the effective use of the models in clinical practice.

Stretching and muscle-performance exercises for chronic nonspecific neck pain: who may benefit most?

BACKGROUND

Although exercise is the mainstay of treatment for neck pain (NP), uncertainty remains over optimal decision-making concerning who may benefit most from such, particularly in the long term.

OBJECTIVE

To identify the subgroup of patients with nonspecific NP most likely to benefit from stretching and muscle-performance exercises.

METHODS

This was a secondary analysis of treatment outcomes of 70 patients (10 of whom dropped out) with a primary complaint of nonspecific NP in one treatment arm of a prospective, randomized, controlled trial. All patients performed the exercises, twice weekly for 6 weeks, and a home exercise program. Blinded outcome measurements were collected at baseline, after the 6-week program, and at a 6-month follow-up. Patients rated their perceived recovery on a 15-point global rating of change scale; a rating of "quite a bit better" (+5) or higher was defined as a successful outcome. Clinical predictor variables were developed via logistic regression analysis to classify patients with NP that may benefit from exercise-based treatment.

RESULTS

NP duration since onset≤6 months, no cervicogenic headache, and shoulder protraction were independent predictor variables. The pretest probability of success was 47% after the 6-week intervention and 40% at the 6-month follow-up. The corresponding posttest probabilities of success for participants with all three variables were 86% and 71%, respectively; such participants were likely to recover.

CONCLUSION

The clinical predictor variables developed in this study may identify patients with nonspecific NP likely to benefit most from stretching and muscle-performance exercises in the short and long terms.

A study protocol for the validation of a prognostic model with an emphasis on modifiable factors to predict chronic pain after a new episode of acute- or subacute nonspecific idiopathic, non-traumatic neck pain presenting in primary care

BACKGROUND

The primary objective of this study is to identify which modifiable and non-modifiable factors are independent predictors of the development of chronic pain in patients with acute- or subacute nonspecific idiopathic, non-traumatic neck pain, and secondly, to combine these to develop and internally validate a prognostic prediction model.

METHODS

A prospective cohort study will be conducted by physiotherapists in 30 primary physiotherapy practices between January 26, 2020, and August 31, 2022, with a 6-month follow-up until March 17, 2023. Patients who consult a physiotherapist with a new episode of acute- (0 to 3 weeks) or subacute neck pain (4 to 12 weeks) will complete a baseline questionnaire. After their first appointment, candidate prognostic variables will be collected from participants regarding their neck pain symptoms, prior conditions, work-related factors, general factors, psychological and behavioral factors. Follow-up assessments will be conducted at six weeks, three months, and six months after the initial assessment. The primary outcome measure is the Numeric Pain Rating Scale (NPRS) to examine the presence of chronic pain. If the pain is present at six weeks, three months, and six months with a score of NPRS ≥3, it is classified as chronic pain. An initial exploratory analysis will use univariate logistic regression to assess the relationship between candidate prognostic factors at baseline and outcome. Multiple logistic regression analyses will be conducted. The discriminative ability of the prognostic model will be determined based on the Area Under the receiver operating characteristic Curve (AUC), calibration will be assessed using a calibration plot and formally tested using the Hosmer and Lemeshow goodness-of-fit test, and model fit will be quantified as Nagelkerke's R2. Internal validation will be performed using bootstrapping-resampling to yield a measure of overfitting and the optimism-corrected AUC.

DISCUSSION

The results of this study will improve the understanding of prognostic and potential protective factors, which will help clinicians guide their clinical decision making, develop an individualized treatment approach, and predict chronic neck pain more accurately.

Exploring visual pain trajectories in neck pain patients, using clinical course, SMS-based patterns, and patient characteristics: a cohort study

Background

The dynamic nature of neck pain has so far been identified through longitudinal studies with frequent measures, a method which is time-consuming and impractical. Pictures illustrating different courses of pain may be an alternative solution, usable in both clinical work and research, but it is unknown how well they capture the clinical course. The aim of this study was to explore and describe self-reported visual trajectories in terms of details of patients’ prospectively reported clinical course, their SMS-based pattern classification of neck pain, and patient’s characteristics.

Methods

Prospective cohort study including 888 neck pain patients from chiropractic practice, responding to weekly SMS-questions about pain intensity for 1 year from 2015 to 2017. Patients were classified into one of three clinical course patterns using definitions based on previously published descriptors. At 1-year follow-up, patients selected a visual trajectory that best represented their retrospective 1-year course of pain: single episode, episodic, mild ongoing, fluctuating and severe ongoing.

Results

The visual trajectories generally resembled the 1-year clinical course characteristics on group level, but there were large individual variations. Patients selecting Episodic and Mild ongoing visual trajectories were similar on most parameters. The visual trajectories generally resembled more the clinical course of the last quarter.

Discussion

The visual trajectories reflected the descriptors of the clinical course of pain captured by weekly SMS measures on a group level and formed groups of patients that differed on symptoms and characteristics. However, there were large variations in symptoms and characteristics within, as well as overlap between, each visual trajectory. In particular, patients with mild pain seemed predisposed to recall bias. Although the visual trajectories and SMS-based classifications appear related, visual trajectories likely capture more elements of the pain experience than just the course of pain. Therefore, they cannot be seen as a proxy for SMS-tracking of pain over 1 year.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12998-022-00443-3.

The association between different outcome measures and prognostic factors in patients with neck pain: a cohort study

Background

Health domains like pain, disability, and health-related quality of life are commonly used outcomes for musculoskeletal disorders. Most prognostic studies include only one outcome, and it is unknown if prognostic factors and models may be generic across different outcomes. The objectives of this study were to examine the correlation among commonly used outcomes for neck pain (pain intensity, disability, and health-related quality of life) and to explore how the predictive performance of a prognostic model differs across commonly used outcomes.

Methods

We conducted an observational prospective cohort study with data from patients with neck pain aged 18–84 years consulting Norwegian chiropractors. We used three different outcomes: pain intensity (Numeric Pain Rating Scale), the Neck Disability Index (NDI), and health-related quality of Life (EQ-5D). We assessed associations between change in outcome scores at 12-weeks follow-up with Pearson’s correlation coefficient. We used multivariable linear regression models to explore differences in explained variance and relationship between predictors and outcomes.

Results

The study sample included 1313 patients and 941 (72%) completed follow-up at 12 weeks. The strongest correlation was between NDI and EQ-5D (r = 0.57) while the weakest correlation was between EQ-5D and pain intensity (r = 0.39). The correlation between NDI and pain intensity was moderate (r = 0.53) In the final regression models, the explained variance ranged from adjusted R² of 0.26 to 0.60, highest with NDI and lowest with pain intensity as outcome. The predictive contributions of the included predictors were similar across outcomes. Among the investigated predictors, pain patterns and the baseline measure of the corresponding outcome measure contributed the most to explained variance across all outcomes.

Conclusions

The highest correlation was found between NDI and EQ-5D and the lowest with pain intensity. The same prognostic model showed highest predictive performance with NDI as outcome and poorest with pain intensity as outcome. These results suggest that we need more knowledge on the reasons for the differences in predictive performance variation across outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05558-5.

Does poor methodological quality of prediction modeling studies translate to poor model performance? An illustration in traumatic brain injury

BACKGROUND

Prediction modeling studies often have methodological limitations, which may compromise model performance in new patients and settings. We aimed to examine the relation between methodological quality of model development studies and their performance at external validation.

METHODS

We systematically searched for externally validated multivariable prediction models that predict functional outcome following moderate or severe traumatic brain injury. Risk of bias and applicability of development studies was assessed with the Prediction model Risk Of Bias Assessment Tool (PROBAST). Each model was rated for its presentation with sufficient detail to be used in practice. Model performance was described in terms of discrimination (AUC), and calibration. Delta AUC (dAUC) was calculated to quantify the percentage change in discrimination between development and validation for all models. Generalized estimation equations (GEE) were used to examine the relation between methodological quality and dAUC while controlling for clustering.

RESULTS

We included 54 publications, presenting ten development studies of 18 prediction models, and 52 external validation studies, including 245 unique validations. Two development studies (four models) were found to have low risk of bias (RoB). The other eight publications (14 models) showed high or unclear RoB. The median dAUC was positive in low RoB models (dAUC 8%, [IQR - 4% to 21%]) and negative in high RoB models (dAUC - 18%, [IQR - 43% to 2%]). The GEE showed a larger average negative change in discrimination for high RoB models (- 32% (95% CI: - 48 to - 15) and unclear RoB models (- 13% (95% CI: - 16 to - 10)) compared to that seen in low RoB models.

CONCLUSION

Lower methodological quality at model development associates with poorer model performance at external validation. Our findings emphasize the importance of adherence to methodological principles and reporting guidelines in prediction modeling studies.

Neck Pain Clinical Prediction Rule to Prescribe Combined Aerobic and Neck-Specific Exercises: Secondary Analysis of a Randomized Controlled Trial

OBJECTIVE

A previous randomized controlled trial revealed that combined aerobic and neck-specific exercises yielded greater improvement than neck-specific exercises alone after a 6-month intervention in outpatients with nonspecific neck pain (NP). The aim of this secondary analysis was to identify subgroups of patients in the combined exercises group most likely to benefit from the intervention.

METHODS

Sixty-nine patients were included. The original trial was conducted in multiple physical therapy outpatient clinics twice a week for 6 weeks; follow-up was 6 months after assignment. The primary outcome was the therapeutic success rate (Global Rating of Change Score ≥ +5, "quite a bit better") after 6 weeks of training and at the 6-month follow-up. Candidate predictors from patients' medical history and physical examination were selected for univariable regression analysis to determine their association with treatment response status. Multivariable logistic regression analysis was used to derive preliminary clinical prediction rules.

RESULTS

The clinical prediction rule contained 3 predictor variables: (1) symptom duration ≤6 months, (2) neck flexor endurance ≥18 seconds, and (3) absence of referred pain (Nagelkerke R2 = .40 and -2 log likelihood = 60.30). The pre-test probability of success was 61.0% in the short term and 77.0% in the long term. The post-test probability of success for patients with at least 2 of the 3 predictor variables was 84.0% in the short term and 87.0% in the long term; such patients will likely benefit from this program.

CONCLUSION

A simple 3-item assessment, derived from easily obtainable baseline data, can identify patients with NP who may respond best to combined aerobic and neck-specific exercises. Validation is required before clinical recommendation.

IMPACT

Patients experiencing NP symptoms ≤6 months who have no referred pain and exhibit neck flexor endurance ≥18 seconds may benefit from a simple self-training program of combined aerobic and neck-specific exercises.

A Comparative Study of a Novel Postural Garment Versus Exercise for Women with Nonspecific Cervical Pain: A Randomized Cross-over Trial

STUDY DESIGN

Randomized cross-over study.

OBJECTIVE

The aim of this study was to compare exercise, the criterion standard, to the postural garment PosturePlusForce in the management of nonspecific cervical pain in women. We also analyzed both interventions with regards to baseline posture, use of pharmacological pain relievers, compliance, and comfort.

SUMMARY OF BACKGROUND DATA

The prevalence of neck pain has increased during the last decade, preferentially affecting women. Those suffering from this condition may manifest a decrease in quality of life and inability to work. Consistent recommendations highlight the importance of exercise and posture for neck pain improvement.

METHODS

A total of 32 female health care professionals with cervical pain (≥3 on the visual analogue scale) entered the trial. Participants were allocated to either performing exercises or wearing the postural garment. The cross-over between interventions was separated by a 3-month washout period. Primary outcomes included pain intensity and posture. Secondary outcomes comprised cervical pain-related disability, psychological factors, physical activity, global perceived effect of treatment, and garment comfort. Treatment compliance, medication use, and adverse events were also recorded.

RESULTS

Both interventions showed a significant improvement in pain in subjects with an adherence >60%. However, in participants with dorsal hyperkyphosis (>45°), the garment demonstrated a greater reduction in pain than exercise (P = 0.019). Additionally, those wearing the garment needed fewer pain relievers than those performing exercises (P = 0.007). Compliance was >50% for both interventions and comfort was contingent on season.

CONCLUSION

In our study, PosturePlusForce showed, at least, a similar effect on pain to exercise, although those with dorsal hyperkyphosis exhibited a greater reduction in pain and related variables with the garment. Pain relievers were less required by those wearing PosturePlusForce than by those performing the exercises.Level of Evidence: 1.

Development and internal validation of prognostic models for recovery in patients with non-specific neck pain presenting in primary care

OBJECTIVES

Development and internal validation of prognostic models for post-treatment and 1-year recovery in patients with neck pain in primary care.

DESIGN

Prospective cohort study.

SETTING

Primary care manual therapy practices.

PARTICIPANTS

Patients with non-specific neck pain of any duration (n=1193).

INTERVENTION

Usual care manual therapy.

OUTCOME MEASURES

Recovery defined in terms of pain intensity, disability, and global perceived improvement directly post-treatment and at 1-year follow-up.

RESULTS

All post-treatment models exhibited acceptable discriminative performance after derivation (AUC≥0.7). The developed post-treatment disability model exhibited the best overall performance (R²=0.24; IQR, 0.22-0.26), discrimination (AUC=0.75; 95% CI, 0.63-0.84), and calibration (slope 0.92; IQR, 0.91-0.93). After internal validation and penalization, this model retained acceptable discriminative performance (AUC=0.74). The five other models, including those predicting 1-year recovery, did not reach acceptable discriminative performance after internal validation. Baseline pain duration, disability, and pain intensity were consistent predictors across models.

CONCLUSION

A post-treatment prognostic model for disability was successfully developed and internally validated. This model has potential to inform primary care clinicians about a patient's individual prognosis after treatment, but external validation is required before clinical use can be recommended.

External validation of prognostic models for recovery in patients with neck pain

Background

Neck pain is one of the leading causes of disability in most countries and it is likely to increase further. Numerous prognostic models for people with neck pain have been developed, few have been validated. In a recent systematic review, external validation of three promising models was advised before they can be used in clinical practice.

Objective

The purpose of this study was to externally validate three promising models that predict neck pain recovery in primary care.

Methods

This validation cohort consisted of 1311 patients with neck pain of any duration who were prospectively recruited and treated by 345 manual therapists in the Netherlands. Outcome measures were disability (Neck Disability Index) and recovery (Global Perceived Effect Scale) post-treatment and at 1-year follow-up. The assessed models were an Australian Whiplash-Associated Disorders (WAD) model (Amodel), a multicenter WAD model (Mmodel), and a Dutch non-specific neck pain model (Dmodel). Models’ discrimination and calibration were evaluated.

Results

The Dmodel and Amodel discriminative performance (AUC < 0.70) and calibration measures (slope largely different from 1) were poor. The Mmodel could not be evaluated since several variables nor their proxies were available.

Conclusions

External validation of promising prognostic models for neck pain recovery was not successful and their clinical use cannot be recommended. We advise clinicians to underpin their current clinical reasoning process with evidence-based individual prognostic factors for recovery. Further research on finding new prognostic factors and developing and validating models with up-to-date methodology is needed for recovery in patients with neck pain in primary care.

Recovery trajectories in common musculoskeletal complaints by diagnosis contra prognostic phenotypes

Background

There are large variations in symptoms and prognostic factors among patients sharing the same musculoskeletal (MSK) diagnosis, making traditional diagnostic labelling not very helpful in informing treatment or prognosis. Recently, we identified five MSK phenotypes across common MSK pain locations through latent class analysis (LCA). The aim of this study was to explore the one-year recovery trajectories for pain and functional limitations in the phenotypes and describe these in relation to the course of traditional diagnostic MSK groups.

Methods

We conducted a longitudinal observational study of 147 patients with neck, back, shoulder or complex pain in primary health care physiotherapy. Data on pain intensity and function were collected at baseline (week 0) and 1, 2, 3, 4, 6, 8, 12, 26 and 52 weeks of follow up using web-based questionnaires and mobile text messages. Recovery trajectories were described separately for the traditional diagnostic MSK groups based on pain location and the same patients categorized in phenotype groups based on prognostic factors shared among the MSK diagnostic groups.

Results

There was a general improvement in function throughout the year of follow-up for the MSK groups, while there was a more modest decrease for pain intensity. The MSK diagnoses were dispersed across all five phenotypes, where the phenotypes showed clearly different trajectories for recovery and course of symptoms over 12 months follow-up. This variation was not captured by the single trajectory for site specific MSK diagnoses.

Conclusion

Prognostic subgrouping revealed more diverse patterns in pain and function recovery over 1 year than observed in the same patients classified by traditional diagnostic groups and may better reflect the diversity in recovery of common MSK disorders.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04332-3.

Prognostic factors for the improvement of pain and disability following multidisciplinary rehabilitation in patients with chronic neck pain

Background

Recent clinical studies have demonstrated the effectiveness of specific, multidisciplinary, bio-psychosocial, rehabilitation programmes for chronic neck pain. However, prognostic factors for the improvement of pain and disability are mostly unknown. Therefore, the aim of this study was to explore prognostic factors associated with improvements in chronic neck pain following participation in a three-week, multidisciplinary, bio-psychosocial, rehabilitation programme.

Methods

In this observational, prospective cohort study, a total of 112 patients were assessed at the beginning, end, and 6 months following the completion of a multidisciplinary, bio-psychosocial, rehabilitation programme. Inclusion for participation in the rehabilitation programme depended upon an interdisciplinary pain assessment. The primary outcome was neck pain and disability, which was measured using the Northern American Spine Society questionnaire for pain+disability and was quantified with effect sizes (ES). Multivariable linear regression analyses were used to explore potential prognostic factors associated with improvements in pain and disability scores at discharge and at the 6-month follow-up period.

Results

The mean age of the patients was 59.7 years (standard deviation = 10.8), and 70.5% were female. Patients showed improvement in pain+disability at discharge (ES = 0.56; p < 0.001), which was sustained at the 6-month follow-up (ES = 0.56; p < 0.001). Prognostic factors associated with improvement in pain+disability scores at discharge included poor pain+disability baseline scores (partial, adjusted correlation r = 0.414, p < 0.001), older age (r = 0.223, p = 0.024), a good baseline cervical active range-of-motion (ROM) (r = 0.210, p < 0.033), and improvements in the Short-form 36 mental health scale (r = 0.197; p = 0.047) and cervical ROMs (r = 0.195, p = 0.048) from baseline values. Prognostic factors associated with improvements in pain+disability at the 6-month follow-up were similar and included poor pain+disability baseline scores (partial, adjusted correlation r = 0.364, p < 0.001), improvements in the Short-form 36 mental health scale (r = 0.232; p = 0.002), cervical ROMs (r = 0.247, p = 0.011), and better cervical ROM baseline scores. However, older age was not a factor (r = 0.134, p = 0.172).

Conclusions

Future prognostic models for treatment outcomes in chronic neck pain patients should consider cervical ROM and mental health status. Knowledge of prognostic factors may help in the adoption of individualized treatment for patients who are less likely to respond to multidisciplinary rehabilitation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04194-9.

Challenges and solutions in prognostic prediction models in spinal disorders

Methodological shortcomings in prognostic modeling for patients with spinal disorders are highly common. This general commentary discusses methodological challenges related to the specific nature of this field. Five specific methodological challenges in prognostic modeling for patients with spinal disorders are presented with their potential solutions, as related to the choice of study participants, purpose of studies, limitations in measurements of outcomes and predictors, complexity of recovery predictions, and confusion of prognosis and treatment response. Large studies specifically designed for prognostic model research are needed, using standard baseline measurement sets, clearly describing participants' recruitment and accounting and correcting for measurement limitations.

Consensus of potential modifiable prognostic factors for persistent pain after a first episode of nonspecific idiopathic, non-traumatic neck pain: results of nominal group and Delphi technique approach

BACKGROUND

Identify and establish consensus regarding potential prognostic factors for the development of chronic pain after a first episode of idiopathic, non-traumatic neck pain.

DESIGN

This study used two consensus group methods: a modified Nominal Group (m-NGT) and a Delphi Technique.

METHODS

The goal of the m-NGT was to obtain and categorize a list of potential modifiable prognostic factors. These factors were presented to a multidisciplinary panel in a two-round Delphi survey, which was conducted between November 2018 and January 2020. The participants were asked whether factors identified are of prognostic value, whether these factors are modifiable, and how to measure these factors in clinical practice. Consensus was a priori defined as 70% agreement among participants.

RESULTS

Eighty-four factors were identified and grouped into seven categories during the expert meeting using the modified NGT. A workgroup reduced the list to 47 factors and grouped them into 12 categories. Of these factors, 26 were found to be potentially prognostic for chronification of neck pain (> 70% agreement). Twenty-one out of these 26 factors were found to be potentially modifiable by physiotherapists based on a two-round Delphi survey.

CONCLUSION

Based on an expert meeting (m-NGT) and a two-round Delphi survey, our study documents consensus (> 70%) on 26 prognostic factors. Twenty-one out of these 26 factors were found to be modifiable, and most factors were psychological in nature.

A conceptual framework for prognostic research

BACKGROUND

Prognostic research has many important purposes, including (i) describing the natural history and clinical course of health conditions, (ii) investigating variables associated with health outcomes of interest, (iii) estimating an individual's probability of developing different outcomes, (iv) investigating the clinical application of prediction models, and (v) investigating determinants of recovery that can inform the development of interventions to improve patient outcomes. But much prognostic research has been poorly conducted and interpreted, indicating that a number of conceptual areas are often misunderstood. Recent initiatives to improve this include the Prognosis Research Strategy (PROGRESS) and the Transparent Reporting of a multivariable prediction model for Individual Prognosis or Diagnosis (TRIPOD) Statement. In this paper, we aim to show how different categories of prognostic research relate to each other, to differentiate exploratory and confirmatory studies, discuss moderators and mediators, and to show how important it is to understand study designs and the differences between prediction and causation.

MAIN TEXT

We propose that there are four main objectives of prognostic studies - description, association, prediction and causation. By causation, we mean the effect of prediction and decision rules on outcomes as determined by intervention studies and the investigation of whether a prognostic factor is a determinant of outcome (on the causal pathway). These either fall under the umbrella of exploratory (description, association, and prediction model development) or confirmatory (prediction model external validation and investigation of causation). Including considerations of causation within a prognostic framework provides a more comprehensive roadmap of how different types of studies conceptually relate to each other, and better clarity about appropriate model performance measures and the inferences that can be drawn from different types of prognostic studies. We also propose definitions of 'candidate prognostic factors', 'prognostic factors', 'prognostic determinants (causal)' and 'prognostic markers (non-causal)'. Furthermore, we address common conceptual misunderstandings related to study design, analysis, and interpretation of multivariable models from the perspectives of association, prediction and causation.

CONCLUSION

This paper uses a framework to clarify some concepts in prognostic research that remain poorly understood and implemented, to stimulate discussion about how prognostic studies can be strengthened and appropriately interpreted.

Relationships Between Context, Process, and Outcome Indicators to Assess Quality of Physiotherapy Care in Patients with Whiplash-Associated Disorders: Applying Donabedian's Model of Care

BACKGROUND

Quality indicators (QIs) are measurable elements of practice performance and may relate to context, process, outcome and structure. A valid set of QIs have been developed, reflecting the clinical reasoning used in primary care physiotherapy for patients with whiplash-associated disorders (WAD). Donabedian's model postulates relationships between the constructs of quality of care, acting in a virtuous circle.

AIM

To explore the relative strengths of the relationships between context, process, and outcome indicators in the assessment of primary care physiotherapy in patients with WAD.

MATERIALS AND METHODS

Data on WAD patients (N=810) were collected over a period of 16 years in primary care physiotherapy practices by means of patients records. This routinely collected dataset (RCD-WAD) was classified in context, process, and outcome variables and analyzed retrospectively. Clinically relevant variables were selected based on expert consensus. Associations were expressed, using zero-order, as Spearman rank correlation coefficients (criterion: rs >0.25 [minimum: fair]; α-value = 0.05).

RESULTS

In round 1, 62 of 85 (72.9%) variables were selected by an expert panel as relevant for clinical reasoning; in round 2, 34 of 62 (54.8%) (context variables 9 of 18 [50.0%]; process variables 18 of 34 [52.9]; outcome variables 8 of 10 [90.0%]) as highly relevant. Associations between the selected context and process variables ranged from 0.27 to 0.53 (p≤0.00), between selected context and outcome variables from 0.26 to 0.55 (p≤0.00), and between selected process and outcome variables from 0.29 to 0.59 (p≤0.00). Moderate associations (rs >0.50; p≤0.00) were found between "pain coping" and "fear avoidance" as process variables, and "pain intensity" and "functioning" as outcome variables.

CONCLUSION

The identified associations between selected context, process, and outcome variables were fair to moderate. Ongoing work may clarify some of these associations and provide guidance to physiotherapists on how best to improve the quality of clinical reasoning in terms of relationships between context, process, and outcome in the management of patients with WAD.

Classifying neck pain status using scalar and functional biomechanical variables - development of a method using functional data boosting

BACKGROUND

Individuals with neck pain have different movement and muscular activation (collectively termed as biomechanical variables) patterns compared to healthy individuals. Incorporating biomechanical variables as covariates into prognostic models is challenging due to the high dimensionality of the data.

RESEARCH QUESTION

What is the classification performance of neck pain status of a statistical model which uses both scalar and functional biomechanical covariates?

METHODS

Motion capture with electromyography assessment on the sternocleidomastoid, splenius cervicis, erector spinae, was performed on 21 healthy and 26 individuals with neck pain during walking over three gait conditions (rectilinear, curvilinear clockwise (CW) and counterclockwise (CCW)). After removing highly collinear variables, 94 covariates across the three conditions were used to classify neck pain status using functional data boosting (FDboost).

RESULTS

Two functional covariates trunk lateral flexion angle during CCW gait, and trunk flexion angle during CW gait; and a scalar covariate, hip jerk index during CCW gait were selected. The model achieved an estimated AUC of 80.8 %. For hip jerk index, an increase in hip jerk index by one unit increased the log odds of being in the neck pain group by 0.37. A 1° increase in trunk lateral flexion angle throughout gait alone reduced the probability of being in the neck pain group from 0.5 to 0.15. A 1° increase in trunk flexion angle throughout gait alone increased the probability of being in the neck pain group from 0.5 to 0.9.

SIGNIFICANCE

Interpreting the physiological significance of the extracted covariates, with other biomechanical variables, suggests that individuals with neck pain performed curvilinear walking using a stiffer strategy, compared to controls; and this increased the risk of being in the neck pain group. FDboost can produce clinically interpretable models with complex high dimensional data and could be used in future prognostic modelling studies in neck pain research.

Predicting the duration of sickness absence spells due to back pain: a population-based study from Sweden

Objectives

We aimed to develop and validate a prediction model for the duration of sickness absence (SA) spells due to back pain (International Statistical Classification of Diseases and Related Health Problems 10th Revision: M54), using Swedish nationwide register microdata.

Methods

Information on all new SA spells >14 days from 1 January 2010 to 30 June 2012 and on possible predictors were obtained. The duration of SA was predicted by using piecewise constant hazard models. Nine predictors were selected for the final model based on a priori decision and log-likelihood loss. The final model was estimated in a random sample of 70% of the SA spells and later validated in the remaining 30%.

Results

Overall, 64 048 SA spells due to back pain were identified during the 2.5 years; 74% lasted ≤90 days, and 9% >365 days. The predictors included in the final model were age, sex, geographical region, employment status, multimorbidity, SA extent at the start of the spell, initiation of SA spell in primary healthcare and number of SA days and specialised outpatient healthcare visits from the preceding year. The overall c-statistic (0.547, 95% CI 0.542 to 0.552) suggested a low discriminatory capacity at the individual level. The c-statistic was 0.643 (95% CI 0.634 to 0.652) to predict >90 days spells, 0.686 (95% CI 0.676 to 0.697) to predict >180 spells and 0.753 (95% CI 0.740 to 0.766) to predict >365 days spells.

Conclusions

The model discriminates SA spells >365 days from shorter SA spells with good discriminatory accuracy.

Multidimensional screening for predicting pain problems in adults: a systematic review of screening tools and validation studies

Screening tools allowing to predict poor pain outcomes are widely used. Often these screening tools contain psychosocial risk factors. This review (1) identifies multidimensional screening tools that include psychosocial risk factors for the development or maintenance of pain, pain-related distress, and pain-related disability across pain problems in adults, (2) evaluates the quality of the validation studies using Prediction model Risk Of Bias ASsessment Tool (PROBAST), and (3) synthesizes methodological concerns. We identified 32 articles, across 42 study samples, validating 7 screening tools. All tools were developed in the context of musculoskeletal pain, most often back pain, and aimed to predict the maintenance of pain or pain-related disability, not pain-related distress. Although more recent studies design, conduct, analyze, and report according to best practices in prognosis research, risk of bias was most often moderate. Common methodological concerns were identified, related to participant selection (eg, mixed populations), predictors (eg, predictors were administered differently to predictors in the development study), outcomes (eg, overlap between predictors and outcomes), sample size and participant flow (eg, unknown or inappropriate handling of missing data), and analysis (eg, wide variety of performance measures). Recommendations for future research are provided.

Prognostic factors for persistent pain after a first episode of nonspecific idiopathic, non-traumatic neck pain: A systematic review

BACKGROUND

Prognosis of acute idiopathic neck pain is poor. An overview of modifiable and non-modifiable prognostic factors for the development of chronic musculoskeletal neck pain after an episode of idiopathic, non-traumatic neck pain is needed.

OBJECTIVE

Identify prognostic factors for pain intensity and perceived non-recovery at three, six and 12 months after a first episode of idiopathic, non-traumatic neck pain.

STUDY DESIGN

Systematic review METHODS: Systematic literature search up to October 21, 2017 for prospective prognostic studies with main outcomes perceived non-recovery and pain intensity. The QUIPS was used for quality assessment.

RESULTS

Out of 2737 screened articles six prospective studies with high-risk-of-bias were identified, analyzing 47 and 43 factors for the outcome variables 'pain intensity' and 'perceived non-recovery', respectively. Based on univariate- and multivariate analyses we found moderate evidence for 'age> 40 years' and 'concomitant back pain' to be prognostic for 'pain intensity'. For the outcome 'perceived non-recovery' at 12 months, we found moderate evidence for both 'a previous period of neck pain' and 'accompanying headache' as prognostic variables for persistent pain, based on univariate analysis. No prognostic factor was found which was retained in more than one multivariate analysis for the outcome variable 'perceived non-recovery'. However, the quality of the evidence for these prognostic factors was low to very low.

CONCLUSION

This review identifies prognostic factors for neck pain, of which only a few are modifiable. Further research is needed before drawing definite conclusions about the prognostic value of these factors.

Prognostic models for predicting overall survival in metastatic castration-resistant prostate cancer: a systematic review

PURPOSE

Prognostic models are developed to estimate the probability of the occurrence of future outcomes incorporating multiple variables. We aimed to identify and summarize existing multivariable prognostic models developed for predicting overall survival in patients with metastatic castration-resistant prostate cancer (mCRPC).

METHODS

The protocol was prospectively registered (CRD42017064448). We systematically searched Medline and reference lists up to May 2018 and included experimental and observational studies, which developed and/or internally validated prognostic models for mCRPC patients and were further externally validated or updated. The outcome of interest was overall survival. Two authors independently performed literature screening and quality assessment.

RESULTS

We included 12 studies that developed models including 8750 patients aged 42-95 years. Models included 4-11 predictor variables, mostly hemoglobin, baseline PSA, alkaline phosphatase, performance status, and lactate dehydrogenase. Very few incorporated Gleason score. Two models included predictors related to docetaxel and mitoxantrone treatments. Model performance after internal validation showed similar discrimination power ranging from 0.62 to 0.73. Overall survival models were mainly constructed as nomograms or risk groups/score. Two models obtained an overall judgment of low risk of bias.

CONCLUSIONS

Most models were not suitable for clinical use due to methodological shortcomings and lack of external validation. Further external validation and/or model updating is required to increase prognostic accuracy and clinical applicability prior to their incorporation in clinical practice as a useful tool in patient management.

Review article: Best practice management of neck pain in the emergency department (part 6 of the musculoskeletal injuries rapid review series)

Neck pain and whiplash injuries are a common presentation to the ED, and a frequent cause of disability globally. This rapid review investigated best practice for the assessment and management of musculoskeletal neck pain in the ED. PubMed, CINAHL, EMBASE, TRIP and the grey literature, including relevant organisational websites, were searched in 2017. Primary studies, systematic reviews and guidelines were considered for inclusion. English-language articles published in the past 12 years addressing acute neck pain assessment, management or prognosis in the ED were included. Data extraction was conducted, followed by quality appraisal to rate levels of evidence where possible. The search revealed 2080 articles, of which 51 were included (n = 22 primary articles, n = 13 systematic reviews and n = 16 guidelines). Consistent evidence was found to support the use of 'red flags' to screen for serious pathologies, judicious use of imaging through clinical decision rule application and promotion of functional exercise coupled with advice and reassurance. Clinicians may also consider applying risk-stratification methods, such as using a clinical prediction rule, to guide patient discharge and referral plans; however, the evidence is still emerging in this population. This rapid review provides clinicians managing neck pain in the ED a summary of the best available evidence to enhance quality of care and optimise patient outcomes.