On 2016 Mar 24, Jeromy Anglim commented:

Thanks for posting a comment. I just wanted to add a few thoughts on your points.

Relationship between type D and outcomes were not moderated by illness group. For us, this was the important conclusion that we want researchers to think about. There is a lot of research done examining Type D in specific illness groups. To some extent implicit in such research is the idea that the effect of Type D might vary based on illness type. While this may be true, this study presents some evidence that at least for the illness groups and variables studied, this is not the case.

The effect of negative affect on social support and the effect of social inhibition on health behaviours failed to reach statistical significance. I would not say that it failed. This is actually an important finding that supports the idea that the subscales of Type D provide different correlates (i.e., negative affectivity is related more to affective processes, and social inhibition is related more to social processes). Presumably, this is as we would expect. Although if you wanted to be critical, there is the idea that NA is merely neuroticism, and SI is a mix of neuroticism and introversion (see Horwood, Anglim, Tooley, 2015). Whether that is a problem probably depends on how primary you view Big 5 personality.

Limitations: I think we note the limitations you mention in the limitations section. That said, those limitations only relate to certain points of the paper. For me personally, I think that the paper has two fairly important implications for researchers working with Type D personality. The first relates to the general lack of variation in effects by group as discussed above. Second, we did a comparative regression analysis comparing a range of different scoring systems for Type D personality. The results suggested that binary Type D is a poor predictor, and there was limited evidence for NA by SI interactions effects. Rather entering NA and SI as two separate predictors generally resulted in the best prediction of outcomes. This goes agains the implicit claims of Type D that there is an interactive effect and that cut-offs are appropriate for Type D. Importantly, all these analyses also speak to the novelty of the Type D construct and the rationale for choosing the two particular subscales for inclusion.

Thus, for me, the paper provides a nuanced and critical assessment of the predictive validity of Type D personality. In particular, I'd encourage other researchers working with Type D personality (and some are doing this already) to run the comparative regression analyses in their samples.

On 2016 Mar 23, Andrew Kewley commented:

Given that the main hypothesis was unsupported by the evidence, it seems strange that there is no mention of this in the abstract.

The hypothesis was stated: "that functional somatic syndromes, conditions that are characterized primarily by general somatic complaints of unclear etiology, such as chronic fatigue syndrome or fibromyalgia, may be more susceptible to the effects of Type D personality than illnesses of known etiology such as type 2 diabetes or arthritis."

The authors did not find a difference in the prevalence of "Type D personality" between the two chronic illness groups. Likewise, the effect of negative affect on social support and the effect of social inhibition on health behaviours failed to reach statistical significance between the two chronic illness groups after correcting for multiple comparisons.

The study had key limitations, in particular it was based on a convenience sample and self-report questionnaires rather than objective measures of symptom impact and social support. The sample size was adequate.

While there was much speculation in the discussion, the most likely directional association between the questionnaire results and illness is simply that chronic illness contributes to affective suffering.

On 2016 Mar 23, Andrew Kewley commented:

Given that the main hypothesis was unsupported by the evidence, it seems strange that there is no mention of this in the abstract.

The hypothesis was stated: "that functional somatic syndromes, conditions that are characterized primarily by general somatic complaints of unclear etiology, such as chronic fatigue syndrome or fibromyalgia, may be more susceptible to the effects of Type D personality than illnesses of known etiology such as type 2 diabetes or arthritis."

The authors did not find a difference in the prevalence of "Type D personality" between the two chronic illness groups. Likewise, the effect of negative affect on social support and the effect of social inhibition on health behaviours failed to reach statistical significance between the two chronic illness groups after correcting for multiple comparisons.

The study had key limitations, in particular it was based on a convenience sample and self-report questionnaires rather than objective measures of symptom impact and social support. The sample size was adequate.

While there was much speculation in the discussion, the most likely directional association between the questionnaire results and illness is simply that chronic illness contributes to affective suffering.