Persistent Post-concussion Symptoms

Study IV aimed to examine the prevalence of, and multiple biopsychosocial factors related to, persistent post-concussion symptom reporting at one month and one year

following MTBI. Also, the study compared two different diagnostic criteria, namely postconcussional syndrome (PCS) per the International Classification of Diseases-10th edition (World Health Organization, 1992) and postconcussional disorder (PCD) per the Diagnostic and Statistical Manual of Mental Disorders-IV.

Compared to the neuropsychological control group, the MTBI group reported a greater number of post-concussion symptoms (Study III, p<.01, d=.76, medium effect size). The MTBI group total score on RPCSQ was significantly higher compared to controls at both one month [t(129)=5.32, p<.001, d=.71] and one year [t(119)=2.48, p=.015, d=.36] following injury. Rivermead Post Concussion Symptoms questionnaire (RPCSQ) for MTBI patients at one month post injury was 10.4 (SD=10.7, Range=0–44). The average score on the RPCSQ at one year post injury was 6.8 (SD=9.6, Range=0–41). The average score on the RPCSQ for the control group was 3.7 (SD=4.9, Range=0–17). The four most common symptoms in the MTBI group at one month were fatigue, tiring more easily, sleep disturbance, feeling frustrated or impatient, and headaches. All these symptoms were reported by more than 10% of patients using the criteria “moderate or greater” symptom reporting.

In MTBI group, fatigue was most frequent symptom using “moderate or greater”

symptom reporting at both one month and one year following injury (Study IV). No one in the control group reported moderate or greater fatigue although a few control subjects reported mild fatigue (8.3%). Also, poor concentration was uniquely reported by MTBI group compared to controls (0%) both one month (9.7%) and one year (7.8%) post-injury (Study IV). In the MTBI group, post-concussion-like symptoms (RPCSQ total score) at both one month and one year following injury had a significant correlation with depressive symptoms (BDI-II total score/ 10 items most reflective of depression) (r=.51, p<.01 at four weeks; r=.59, p<.01 at 12 months).

5.2.3.1 Prevalence of Postconcussional Disorder /Postconcussional syndrome

The rate at which the PPCS is diagnosed was significantly lower using the DSM-IV criteria versus the ICD-10 criteria. Also, the rate of diagnosis using both systems was significantly lower if symptoms were conceptualized as “moderate or greater” on the rating scale versus simply being present (i.e., “mild or greater”).

5.2.3.2 ICD-10 Postconcussional Syndrome

Using the mild or greater ICD-10 criteria for PCS, 59% of the MTBI cases met criteria at one month post injury and 38% met criteria at one year post injury. In the control group, 31% met the criteria. Using the moderate or greater ICD-10 criteria for the PCS, 20% of the MTBI cases met criteria at one month post injury and 12% met criteria at one year. In the control group, 0% met the criteria. At one month post injury, a significantly greater proportion of MTBI patients met PCS criteria than control participants using symptom endorsement as “mild or greater” [χ²(1,160) = 8.97, p=.003] and “moderate or greater” [χ²(1,158) = 8.35, p=.007]. At one year post-injury, a significantly greater proportion of MTBI patients met PCS criteria compared to controls when using

“moderate or greater” criterion [χ²(1,139) = 4.59, p=.036].

5.2.3.3 DSM-IV Postconcussional Disorder

Using the mild or greater DSM-IV criteria for PCD, only 1.6% of the MTBI cases met criteria at one month post injury, and 1.0% met criteria at one year. In the control group, 0% met the criteria. Using the moderate or greater DSM-IV criteria for the syndrome, 0% of the MTBI cases met criteria one month post injury, and 1.0% met criteria at one year. None of the controls met the criteria. There were too few cases of PCD to run statistical analysis. All patients who met DSM-IV PCD criteria also fulfilled ICD-10 PCS criteria.

5.2.3.4 Correlates of Persistent Post-concussion Symptoms

Post-injury depression was strongly associated with a diagnosis of the PCS. There was a significant positive Pearson correlation between the BDI-II subscale scores (i.e., the 10 items most reflective of depression) and the RPSQ total scores in the MTBI group at one month post injury (r=.51; p<.001) and at one year post injury (r=.59; p<.001). Of the 73 patients who met criteria for PCS at one month post injury based on “mild or greater”

symptom reporting, 9.6% also met criteria for concurrent depression [χ²(1,126)=5.18, p=.02]. Of the 24 patients who met criteria for PCS at one month post injury based on

“moderate or greater” symptom reporting, 16.7% met criteria for concurrent depression [χ²(1,126)=8.82, p< 0.01]. Of the 39 patients who met criteria for PCS at one year post injury based on “mild or greater” symptom reporting, 7.7% met criteria for concurrent depression [χ²(1,103)=1.05, p=.30]. Of the 12 patients who met criteria for PCS at one

year post injury based on “moderate or greater” symptom reporting, 25% met criteria for concurrent depression [χ²(1,103)=11.78, p< 0.01].

Those with a pre-injury history of mental health problems were more likely to have PCS at one month. Of the 73 patients who met ICD-10 criteria for PCS at one month post injury based on “mild or greater” symptom reporting, 10.9% (n=8) had previous mental health problems [χ² (1,126)=3.61, p=.080]. Of those 8 patients, who had a history of mental health problems, 88.9% met the ICD-10 criteria for PCS based on “mild or greater” symptom reporting. Using symptom endorsement as “moderate or greater” in those with a pre-injury mental health problem (n=8), 62.5% [χ² (1,122)=9.94, p=.007]

met the PCS criteria at one month. At one year, there was not a significant association between PCS group membership and previous mental health problems.

5.2.3.5 Post-concussion Symptom Reporting Trajectory

The natural history of post-concussion symptom reporting from one month to one year post-injury was examined in each individual MTBI subject (n=101). (Study IV, see unpublished Figure 5).

Of the 58 patients who met criteria for ICD-10 PCS at one month based on “mild or greater” symptom reporting, 53.4% (31 patients) met and 46.6% (27 patients) did not meet the PCS criteria at one year. Of those 43 patients who did not meet the ICD-10 PCS criteria (“mild or greater” symptom reporting”) at one month, 16.3% (7 patients) met and 83.7% (36 patients) did not meet the PCS criteria at one year. Those initially met criteria for PCS based on “moderate or greater” symptom reporting, 79% improved and 10% remained symptomatic (met the PCS criteria at one-year follow-up).

At one year, there were seven cases of delayed-onset PCS with “mild or greater”

symptom reporting (18%; 7/38) and eight cases with “moderate or greater” symptom reporting (67%, 8/12). Of those 12 patients who met the PCS criteria at one year based on “moderate or greater” symptom reporting, 66.7% (8 patients) did not meet the criteria based on “moderate or greater” symptom reporting at one month. However, there were only two cases (1.9%, 2/103) that can be considered “pure” delayed-onset PCSs based on “moderate or greater” symptom reporting: these patients did not meet the PCS criteria for even “mild or greater” symptom criteria at four weeks. Thus, a significant minority of patients got worse during the follow-up. From those patients, who did not met the criteria for PCS based on mild or greater symptom reporting at one month post injury, over 16% reported more symptoms at the follow-up and were diagnosed as having PCS at one year following injury. Based on moderate or greater symptom reporting, almost 10% of the PCS absent group at one month post-injury

met the diagnosis of PCS at 12 month follow-up. In sum, of those who initially met the criteria ICD-10 criteria (mild or greater symptom reporting) for PCS (n=58), 46.6%

improved and 53.4% remained symptomatic. Of those who did not meet the ICD-10 PCS criteria at one month (n=43), 16.3% worsened and met the criteria at one year.

5.3 Social Factors