Nagesh Vyenktesh Gaddam¹, Smita Maharudrappa Chakote², Ajay Govindrao Ovhal^3*

¹Assistant Professor, ²Professor, Department of Skin and VD, VMGMC, Solapur, Maharashtra, INDIA.

²Professor, Department of Skin and VD, Government Medical College, Latur, Maharashtra, INDIA.

Email: gnagesh0418@gmail.com, chakote_smita@rediffmail.com, drajayovhal@gmail.com

Table 1: Psoriatic Arthropathy with Age and Sex predilection

There was a male preponderance seen in the patients with psoriatic arthropathy but it was not statistically significant (chi square=2.04, df=1, P=0.153 NS). This was true of all the subtypes, except in the RA like subgroup where female predominance was seen. The male preponderance was most prominent in the oligoarticular group (6:1). Most common type of arthritis in our study population was RA like (33.33%) followed by oligo-articular type (29.16%).

Table 2: Average Age of Patients at Examination of PSA

The average age at presentation of DIP predominant arthritis was 38.3 years. This was 42.62 years for RA like type. The average age at presentation of other varieties fell between these years. The average age of onset of PSA for females was 37.5 years and in males it was 38.53 years. The difference was not significant (t=0.199, P=0.844). The average time by which skin preceded joint involvement was 6.375 years. Arthropathy occurred after skin lesions of psoriasis in 12.5% of patients at an average of 3.33 years. The occurrence of skin disease before Arthropathy was found to be significantly more i.e. in 21 out of 24 patients (83.3%). (Chi square=9.3, df=1, P=0.002 Sig) The number of DIP joints involved on the right side (11) was lesser than the left (20). However, the numbers of the PIP (14) and MCP (13) joints involved on the right side were more than the left (6 and 8). The total number of joints involved on the right side were almost same as left (42 joints as compared to 37). The maximum number of patients in each of the subtypes of arthritis, had only few skin lesions i.e. <30%. The average number of joints affected per patient varied between 4 and 10.75%. A significantly higher number of Psoriatic arthropathy patients had skin involvement less than 30% (Mann Whitney Z =20193, P=0.027 Sign).

Table 3: Type of skin involvement with respect to sex predilection and subtype of arthritis

Significantly higher number of patients i.e. 21 out of 24 (87.5%) had chronic plaque type of psoriasis (chi square=12.04, df=1, P<0.001 HS). The average number of joints affected in chronic plaque type of psoriasis was 5.71.Maximum number (9 of 24) of psoriatic arthropathy patients had skin disease of duration 2-5 years. The average number of joints involved in patients with disease duration less than 5 years was 3.93 whereas with disease duration ≥ 5years it was 7.7, however the difference was not statistically significant (Mann Whitney Z=1.60, P=0.110 NS).

Table 4: Nail changes with respect to duration of PSA

A significantly higher number of patients i.e 21 out of 24 (87.5%) had nail changes (chi square=12.04, df=1, P<0.001 HS). Out of these 20(95.2%) had Thimble pitting.

Table 5: Nail changes with respect to type of psoriatic arthropathy

Pitting was the most frequent seen change seen in the RA like arthritis, followed by ridging. Normal nails were found in only 3 out of 24 patients i.e. 12.5%.

Table 6: Radiological findings with respect to duration of PSA

Most of the radiographs taken within six months of joint involvement revealed either no radiological abnormality or only soft tissue tissue swelling. The radiographs taken after 2 years or more demonstrated joint involvement with erosive and proliferative changes.Among the DIP predominant and RA like type of PSA, soft tissue swelling was the most commonly reported change. Among the spondyloarthropathies, several changes were found like sacroilitis, irregularity of vertebra etc. A few among these had peripheral joint involvement showing erosion, periosteal reaction and soft tissue swelling.

Table 7: Radiological findings with respect to type of PSA

DISCUSSION

The average age of onset of arthropathy in this study was 38.18 years. This is in accordance with world literature, where the onset of psoriatic arthropathy is between third and fifth decades.^3,4 However, Prasad et al⁶ in his study encountered maximum number of patients (16 out of 40,i.e.40%) in 6^th decade. The male to female ratio in PSA has been reported to be equal in some studies^3,4 whereas others mention a slight female preponderance.^2,7,8 Indian studies have documented a significant male preponderance in PSA,^8,9 which is in concordance with our study in which the males outnumber the females in a ratio of 2:1 which was not statistically significant. The number of males exceeded the females in each of the subgroups except in RA like arthritis where 3 of the patients were male, the other 5 were female out of which 6 (75%) had chronic plaque psoriasis. The commonest type of psoriatic arthropathy, in this study was the RA like type, which accounted for 33.33% of the cases (n=8). Most of the Indian study results are consistent with our study.^9,10 Chaudhary et al⁹ from Chandigarh, reported most common type psoriatic arthropathy to be RA like type (33.3%). A recent study from South India by Rajendran et al,¹¹ who had demonstrated commonest type of arthropathy as RA like type (48.3%). However, Prasad et al⁶ reported most common type to be oligoarthritic type (42.5%).This may mean that the RA like type of PSA appears to be the most predominant type in Indian subcontinent as against West where oligoarticular type of arthritis appears most common as reported by Moll et al.⁷ The second commonest type of psoriatic arthritis in the current study was oligoarthritic type (7 out of 24 patients i.e.29%). This is the commonest subtype reported amongst the studies from West as described by Moll and Wright.⁷ In our study 8.33% of patients had sacroilitis. Some studies have reported radiological evidence of sacroilitis in up to 78% of patients.⁵ The most characteristic type of PSA i.e. DIP predominant type was found in 12.5% of patients with the male to female ratio being 2:1.The percentage of DIP predominant type is 5% as per Moll and Wright⁷ with other studies¹² quoting values between 5 and 6%. Studies from India show a percentage varying between 6.1 and 16%.^9,10DIP joint involvement was seen in 41.66% of patients. This is in comparison with other studies from both India¹¹ and abroad^2,7 where DIP involvement ranged between 26-32.6%. A single study done by Chaudhary et al⁹ from India shows a much percentage of DIP joint arthritis i.e. 66.6%. Studies from India a done by Chaudhary et al⁹ and Rajendran et al¹¹ report that around 56-63% of patients have PIP joint arthropathy whereas in world literature^2,7 this type of joint involvement is less commonly involved (41-49%). In the present series 37.5% of patients had PIP joint arthritis. Among the large peripheral joints the most frequently involved joint was ankle (25%). This number is much lower than what is quoted in other studies from India^9,11 and abroad (23-50% in ankle). Axial involvement was observed in 25% with sacral involvement in 8.33% in our study group. This has been discussed in types of PSA.A statistically significant number of patients (21 out of 24, 87.5%) had Nail changes. Studies from India report frequency of patients with nail changes between 30.2%³¹ and 76%²⁰. As per literature nail changes can be seen in 80%^2,7 and can be as high as 90%¹¹ of patients with psoriatic arthritis. Among all types of PSA, the most frequently observed nail change was thimble pitting (95.2%), followed by ridging in 57.14%. Choudhary et al,⁹ also found pitting to be the commonest nail change in PSA as thimble pitting in 66.6% followed by ridging in 53.4% of patients. Discolouration (42.85%) and onycholysis (33.33%) were also reported in our study group. The study done by Choudhary et al⁹ found a higher percentage of onycholysis (50%). They have not reported subungual hyperkeratosis but their study found an increased percentage of nail plate thickening (50%), whereas in our study nail plate thickening was found only in 4.16%. Oil spot, which is an uncommon finding, was present in 8.33% of the present study group as compared to 3.3% in the study by Choudhary et al.⁹ The other clinical studies from India have not mentioned the percentages of various types of nail involvement in PSA.^9,11 Patients with arthropathy of 1-2 yrs duration showed the maximum number of nail changes. Among these pitting was the most common (100%), followed by ridging (60%), discoloration of nail plate (60%), onycholysis (60%) and oil spot (40%). Patient with duration of joint involvement between 2 and 10 years also showed an increase in the number of nail changes but those in whom the duration of arthropathy was greater than 10 years hardly showed any nail involvement. Most of these patients had chronic plaque type of psoriasis. Many patients (25%) in the group with arthropathy of less than 6 months duration did not demonstrate any radiological change, even in symptomatic joint, i.e. they showed normal radiographs. The majority of the patients (50%) with duration of arthropathy less than 6 months had only soft tissue swelling without erosive or proliferative changes. This is to be expected as erosive changes occur only after the joint suffers the insult for certain duration of time.^13,14 After the erosive changes have set in reparative changes start; occasionally erosive and reparative changes occur simultaneously.^13,14The reverse picture also holds true, it was observed that as duration of arthropathy increased, the number of cases with soft tissue swelling decreased with increase in the erosive and proliferative changes. The number of joints with ankylosis was highest in those with arthropathy for periods longer than 10 years. Erosion at the tip and base of terminal phalanx and new bone formation was the most common finding in this group. Periosteal reaction and erosion at the tip/base of the middle phalanx were present in the other group with joint involvement between 6 months and 10 years. As there is no data correlating the duration of arthropathy with radiological changes, these parameters could not be compared. In symmetric polyarticular (RA like) subset of PSA, 56.41% of clinically involved joints showed normal radiology. In those with radiological changes soft tissue swelling was the commonest abnormality found. The majority of patients with this subtype of arthropathy had duration of involvement less than 6 months. This reflects the fact that this type of arthritis occurs in an acute or sub acute setting where erosive and proliferative changes have not had time to set in.^13,14 In the DIP predominant type of PSA, the commonest finding was soft tissue swelling. Rest of the patients showed no radiological abnormality. Most of the oligoarticular type patients had either normal radiological features or decreased joint space. New bone formation and erosion of the base of middle phalanx were amongst the prominent changes in those patients with radiological involvement. There is no data correlating the radiological characteristics with various types of arthropathy except for spondyloarthropathy. Therefore, it was not possible to compare the above mentioned radiological changes with previous data. Majority of patients in the study did not complain of symptoms of axial involvement. Only 6 out of 24 patients had complaints suggestive of axial involvement. They were radiologically investigated. All of them had radiological evidence of arthritis. This high percentage could be because radiographs of the spine were taken in symptomatic patients alone. It is also known that many patients who are asymptomatic could have radiological changes of PSA,¹⁵ but this could not be assessed in our study, as X-rays were taken only if the patients complained of joint pains. Four patients with spondyloarthropathy also had peripheral joint involvement (small joints of hand). This is in agreement with the fact that patients with spondyloarthropathy can also have peripheral joint involvement.^7,15Non-marginal or paravetebral syndesmophytes which are known to be specific to PSA, were seen in 5.6 % of psoriatic arthropathy patients in the study done by Rajendran et al.¹¹ However, no paravetebral syndesmophytes were seen in our study. This could be because we could have missed out radiological changes in the axial skeleton as spine X rays were taken only for symptomatic patients (6 out of 24). Studies from India have reported presence of syndesmophytes of the marginal variety in psoriatic spondyloarthropathy patients.^16,17 In our study none of the patient had vertebral syndesmophyte. Vertebral squaring which has been reported in various studies is usually seen in ankylosing spondylosis, not in PSA.¹³ The various Indian studies that have reported a vertebral squaring are by Mittal et al¹⁶ and Rajendran et al¹¹ who reported an incidence of 7.2 and 0.86% respectively. In the present study there was no vertebral squaring seen similar to a study by Kalam et al.⁸There was only one patient with cervical involvement in our study which is consistent with the fact that cervical spine is less commonly involved in PSA.¹³ In a large retrospective study done in South India, no case of cervical involvement was found.¹¹ One isolated report indicates that cervical involvement is common in PSA.¹⁵ The study on cervical involvement in psoriasis done by Bannerjee et al¹⁶ showed that changes like anterior proliferation, apophyseal narrowing, sclerosis, calcification of anterior ligament, marginal erosion can be appreciated in PSA.¹⁶ Another study on the radiological changes in PSA from Patiala, Punjab shows cervical spine involvement in 7.3% of patients.¹⁶ Two among the six spondyloarthropathy patients (33.33%) had radiologically evident sacroilitis. Sacroilitis is reported to occur in 20-40% of patients with psoriatic spondyloarthropathy.¹⁵ However Ruderman reports that up to 70% of patients with psoriatic spondyloarthropathy may show radiological evidence of sacroilitis.⁵ In the study done by Mittal, Gupta and Kaur on 41 patients of PSA, where radiological examination of spine was done in all patients, sacroiliac joint involvement was present in 27% of patients.¹⁷ 13 among 116 patients (11.2%) were found to have radiologically evident sacroilitis in the study done in South India.¹¹ No patient presented with calcaneal spur. These ill-defined spurs are known to occur because of erosive/proliferative bone changes occurring at sites of attachments of plantar aponeurosis or Achilles’ tendon to the calcaneum. (enthesitis).¹³ Calcaneal spur was seen in 1 patient (0.5%) in the study done by Kalam et al.⁸ A few studies done in India^9-11 did not detect any calcaneal spurs on radiology, which shows that this is an uncommon finding in PSA. One of these found tendoachilles calcification in 3.5% of joints observed radiologically.¹¹ In our study we did not detect calcification of tendoachilles. The limitation in the radiological evaluation of the present study was that radiographs were taken only for symptomatic joints because of which some radiological features in asymptomatic or clinically uninvolved joints could have been missed. This is especially true of spondyloarthropathy as it is documented that this is often asymptomatic, but can still demonstrate radiological changes. Radiographs of all joints irrespective of symptoms were not done, to avoid financial burden to the patient.

CONCLUSION

The commonest type of psoriatic arthropathy, in this study was the RA like type. Maximum number of PSA patients had skin involvement <30% mostly with chronic plaque type. The commonest nail change documented was thimble pitting followed by ridging. Patients with longer duration of arthropathy showed more erosive and prolifertive changes. Overall soft tissue swelling was the commonest radiographic change observed.

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